Category Archives: Climatology

August 2017 weather recap: Cooler than normal with near average precipitation

The last full summer month of the year has come to a close in a rather un-dramatic fashion.  Thornton saw a largely pleasant month with temperatures a good bit cooler than we usually expect to see. Precipitation was right near normal however, all of it fell during the first half of the month.

High pressure ruled for the first two days of the month but then the ridge broke down bringing about cooler temperatures on the 3rd of the month. The cool down didn’t last long and while the heat returned for a couple of days, we did finally receive some moisture on the 4th and 5th.

Cooler than normal temperatures returned on the 6th and lasted through the next 10 days.  The first half of the month also saw 10 days with measurable precipitation, our only precipitation for the month as the last half of the month saw none at all.

Dry and warm conditions were the rule of thumb for the last two weeks of the month.  Both Thornton and Denver saw six of the last nine days of the month bring high temperatures at or above 90 degrees.

Our average temperature for the month came in at 68.9 degrees.  This was a good bit below the long term Denver average for August of 72.5 degrees.  Out at DIA where the Mile High City’s official measurements are taken, the month was warmer than us but still cooler than normal with an average of 71.5 degrees.

Temperatures in Thornton ranged from a high mark reading of 94.9 degrees on the 29th of the month down to a low of 51.2 degrees on the 11th.  Denver saw a maximum reading of 95 degrees on the 19th of the month and a low of 51 degrees on the 4th.

In terms of precipitation, Denver averages 1.69 inches of precipitation during August.  Thornton wasn’t too far short of that with 1.43 inches.  However, all of that came during the first 15 days of the month. After that, we saw nothing.  Denver best us, and the average, with 1.86 inches in their rain bucket.

Click here to view Thornton’s August 2017 climate report.

Thornton, Colorado's August 2017 Temperature Summary. (ThorntonWeather.com)
Thornton, Colorado’s August 2017 Temperature Summary. (ThorntonWeather.com)

Thornton, Colorado's August 2017 Precipitation Summary. (ThorntonWeather.com)
Thornton, Colorado’s August 2017 Precipitation Summary. (ThorntonWeather.com)

CLIMATE REPORT
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
639 PM MDT FRI SEP 1 2017

...................................

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF AUGUST 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1872 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH             105   08/08/1878
 LOW               40   08/26/1910
                        08/25/1910
                        08/24/1910
HIGHEST            95   08/19        96      -1       97  08/09
LOWEST             51   08/04        50       1       47  08/25
                                                          08/20
AVG. MAXIMUM     85.7              87.2    -1.5     86.3
AVG. MINIMUM     57.3              57.9    -0.6     56.2
MEAN             71.5              72.5    -1.0     71.2
DAYS MAX >= 90     10              11.5    -1.5       15
DAYS MAX <= 32      0               0.0     0.0        0
DAYS MIN <= 32      0               0.0     0.0        0
DAYS MIN <= 0       0               0.0     0.0        0

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         5.85   1979
 MINIMUM         0.02   1924
TOTALS           1.86              1.69    0.17     0.22
DAILY AVG.       0.06              0.05    0.01     0.01
DAYS >= .01         6               8.6    -2.6        4
DAYS >= .10         4               4.3    -0.3        1
DAYS >= .50         2               1.2     0.8        0
DAYS >= 1.00        0               0.3    -0.3        0
GREATEST
 24 HR. TOTAL    0.90   08/07 TO 08/07           08/24 TO 08/24

SNOWFALL (INCHES)
RECORDS TOTAL     0.0
TOTALS            0.0 2017          0.0


DEGREE_DAYS
HEATING TOTAL       8                10      -2       15
 SINCE 7/1          8                16      -8       15
COOLING TOTAL     216               244     -28      218
 SINCE 1/1        749               688      61      762

FREEZE DATES
RECORD
 EARLIEST     09/08/1962
 LATEST       06/08/2007
EARLIEST                        10/07
LATEST                          05/05
.........................................................

WIND (MPH)
AVERAGE WIND SPEED              9.2
RESULTANT WIND SPEED/DIRECTION   2/189
HIGHEST WIND SPEED/DIRECTION    49/320    DATE  08/04
HIGHEST GUST SPEED/DIRECTION    62/320    DATE  08/04

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR            7
NUMBER OF DAYS PC             21
NUMBER OF DAYS CLOUDY          3

AVERAGE RH (PERCENT)     50

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM             13     MIXED PRECIP               0
HEAVY RAIN                3     RAIN                       4
LIGHT RAIN               12     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                      10     FOG W/VIS <= 1/4 MILE      2
HAZE                      2

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.

Denver sets a new record high temperature for September 3

Record High TemperaturesWhew! Is this September or July?  As expected the mercury kept on climbing today and did indeed get into record-setting territory.

At 1:53pm the temperature at Denver International Airport where the Mile High City’s official records are kept reached 97 degrees.  This easily bests the previous record high for the date of 95 degrees set in 1995.

Additionally the reading tied the record for hottest September temperature.  Six other times in the past the mercury reached 97 degrees during September occurring on September 1, 1995, September 4, 1960, September 4, 1995, September 5, 1899, September 5, 2013, and September 6, 2013.

Here in Thornton, we were actually warmer than DIA (a rarity).  Temperatures here topped out at 98.5 degrees at 1:20pm.

While above normal temperatures (but not record-setting) are expected for tomorrow, we do expect to see a significant cool down Tuesday then see things bounce back to readings a bit above normal for the balance of the week. See the extended forecast here.

Thornton’s September weather preview: A typically pleasant month

Following on what was a cool but dry August, some are certainly hoping for a bit of precipitation.  The month can bring plenty of rain and even our first snow of the season but more often than not, it is one of the most pleasant along the Colorado Front Range.

As temperatures start to drop, September usually reminds us that summer is at an end and fall is now here. Sunshine is predominant though as the month actually has the highest percentage of sun out of any month. Sunny days and clear, cool nights are the standard weather pattern for the month.

The month can bring extremes however.  We will of course forever remember 2013’s devastating floods brought on by record-setting rain.  Longtime residents might remember September 1971 which brought over 17 inches of snowfall.

Get a complete look at September’s weather and more details as to what we can expect this year here.

July 2017 weather recap: Thornton sees average temps but little precipitation

The month of July might have seemed quite hot but in fact mercury readings were right near normal. What likely caused the misconception is the fact that we saw far less than normal rain.

High pressure did dominate for much of the month and while monsoonal flow did bring rain to eastern Colorado, it largely missed our area.  The Palmer Divide and southeastern Colorado were beneficiaries for much of the month but for us it wasn’t until the last week that we saw relief.

Thornton’s average temperature for the month came in at 74.1 degrees.  This is almost exactly matches Denver’s long-term July average of 74.2 degrees.  Out at DIA where the Mile High City’s official temperatures are taken, it shows a far warmer month with an average of 76.4 degrees.

Temperatures here ranged from a maximum of 99.2 degrees on the 19th down to a low of 50.1 degrees on the morning of the 1st.  Out at the airport, their highest reading was actually 100 degrees seen on the 6th and again on the 19th.  The low out there was 51 degrees on the 1st.

On average Denver receives 2.16 inches of precipitation during July.  Both Thornton and Denver fell far short of that mark.  We managed to record 0.61 inches in our bucket during the month, more than half of which fell on the second to last day of the month. At DIA, Denver recorded 0.47 inches.

Click here to view Thornton’s July 2017 climate report.

Thornton, Colorado's July 2017 temperature summary. (ThorntonWeather.com)
Thornton, Colorado’s July 2017 temperature summary. (ThorntonWeather.com)
Thornton, Colorado's July 2017 precipitation summary. (ThorntonWeather.com)
Thornton, Colorado’s July 2017 precipitation summary. (ThorntonWeather.com)

From the National Weather Service:

CLIMATE REPORT
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
656 AM MDT TUE AUG 1 2017

...................................

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF JULY 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1872 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH             105   07/20/2005
 LOW               42   07/04/1903
                        07/31/1873
HIGHEST           100   07/19        99      -5      102  07/10
                        07/06
LOWEST             51   07/01        51       9       51  07/12
AVG. MAXIMUM     91.5              89.4     2.1     92.0
AVG. MINIMUM     61.3              58.9     2.4     60.5
MEAN             76.4              74.2     2.2     76.2
DAYS MAX >= 90     20              16.0     4.0       22
DAYS MAX <= 32      0               0.0     0.0        0
DAYS MIN <= 32      0               0.0     0.0        0
DAYS MIN <= 0 0 0.0 0.0 0 
PRECIPITATION (INCHES) 
RECORD
 MAXIMUM 6.41 1965
 MINIMUM 0.01 1901 
TOTALS 0.47 2.16 -1.69 1.07 
DAILY AVG. 0.02 0.07 -0.05 0.03 
DAYS >= .01         6               8.3    -2.3        6
DAYS >= .10         3               4.3    -1.3        4
DAYS >= .50         0               1.4    -1.4        1
DAYS >= 1.00        0               0.7    -0.7        0
GREATEST
 24 HR. TOTAL    0.15   07/21 TO 07/21           07/01 TO 07/01
                                                          06/30 TO 07/01
                                                          07/01 TO 07/01

SNOWFALL (INCHES)
RECORDS TOTAL      0.0
 TOTALS            0.0 2017         0.0

DEGREE_DAYS
HEATING TOTAL       0                 6      -6        0
 SINCE 7/1          0                 6      -6        0
COOLING TOTAL     360               289      71      356
 SINCE 1/1        533               444      89      544

FREEZE DATES
RECORD
 EARLIEST     09/08/1962
 LATEST       06/08/2007
EARLIEST                        10/07
LATEST                          05/05
..................................................

WIND (MPH)
AVERAGE WIND SPEED              9.6
RESULTANT WIND SPEED/DIRECTION   3/204
HIGHEST WIND SPEED/DIRECTION    45/120    DATE  07/15
HIGHEST GUST SPEED/DIRECTION    53/120    DATE  07/15

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR            6
NUMBER OF DAYS PC             21
NUMBER OF DAYS CLOUDY          4

AVERAGE RH (PERCENT)     45

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              9     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       3
LIGHT RAIN                9     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                       3     FOG W/VIS <= 1/4 MILE      1
HAZE                      3

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.

Thornton’s August weather preview: Forecasts indicate cooler, wetter weather

As summer vacations wind down and families prepare to send their kids back to school in August, Colorado weather also starts to settle down. The chances for severe weather decrease markedly during August and by the end of the month daytime temperatures are dropping quite a bit as well.

Find out more about what lies ahead with Thornton’s August weather here.

June 2017 weather recap: Month offers up warmer, drier than normal conditions

High pressure was the general rule for much of the month of June 2017.  This resulted in overall average temperatures that were warmer than normal and precipitation that fell a good ways short of average.

The month was largely short on weather excitement, beyond the temps and lack of precipitation.  The National Weather Service said that 23 of the 30 days saw above normal temperature readings.  Denver recorded only five days with precipitation while in Thornton we saw eight.

Thornton saw an overall average monthly temperature of 69.2 degrees.  Out at DIA where Denver’s official measurements are taken, the Mile High City was close with an average of 69.5 degrees.  Both locations’ readings were well above the long term June average of 67.4 degrees.

Temperatures in Thornton ranged from a high of 98.7 degrees on the 21st down to a low of 46.3 degrees on the morning of the 24th.  Denver saw a maximum of 99 degrees on the 20th and a low of 42 degrees on the 13th.

In terms of precipitation, Denver averages 1.98 inches during the month of June. Thornton fell short of the mark with 1.20 inches falling into our rain bucket while Denver’s reading was far worse with a mere 0.33 inches falling there.

Neither Thornton nor Denver saw any snowfall during the month.

Click here to view Thornton’s June 2017 climate report.

Thornton, Colorado's June 2017 temperature summary. (ThorntonWeather.com)
Thornton, Colorado’s June 2017 temperature summary. (ThorntonWeather.com)
Thornton, Colorado's June 2017 precipitation summary. (ThorntonWeather.com)
Thornton, Colorado’s June 2017 precipitation summary. (ThorntonWeather.com)

From the National Weather Service:

CLIMATE REPORT
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
729 AM MDT SAT JUL 1 2017

...................................

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF JUNE 2017...

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1872 TO 2017

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH             105   06/26/2012
                        06/25/2012
  LOW              30   06/02/1951

HIGHEST            99   06/20        96       3       98  06/21
LOWEST             42   06/13        42       0       49  06/02
AVG. MAXIMUM     85.5              82.4     3.1     85.5
AVG. MINIMUM     53.6              52.3     1.3     56.2
MEAN             69.5              67.4     2.1     70.8
DAYS MAX >= 90      9               7.9     1.1       12
DAYS MAX <= 32      0               0.0     0.0        0
DAYS MIN <= 32      0               0.0     0.0        0
DAYS MIN <= 0 0 0.0 0.0 0 
PRECIPITATION (INCHES) 
RECORD
 MAXIMUM 4.96 1882
 MINIMUM T 1890 
TOTALS 0.33 1.98 -1.65 1.62 
DAILY AVG. 0.01 0.07 -0.06 0.05 
DAYS >= .01         5               8.4    -3.4        7
DAYS >= .10         2               4.6    -2.6        4
DAYS >= .50         0               1.4    -1.4        1
DAYS >= 1.00        0               0.3    -0.3        0
GREATEST
 24 HR. TOTAL    0.13   06/29 TO 06/29           06/13 TO 06/13

SNOWFALL (INCHES)
RECORD            0.5 1953
 TOTAL            0.0 2017          0.0

DEGREE_DAYS
HEATING TOTAL      25                62     -37        4
 SINCE 7/1       5109              6058    -949     5560
COOLING TOTAL     167               133      34      185
 SINCE 1/1        173               155      18      188

FREEZE DATES
RECORD
 EARLIEST     09/08/1962
 LATEST       06/08/2007
EARLIEST      04/01             10/07
LATEST        05/04             05/05
....................................................

WIND (MPH)
AVERAGE WIND SPEED              10.1
RESULTANT WIND SPEED/DIRECTION   2/135
HIGHEST WIND SPEED/DIRECTION    44/270    DATE  06/27
HIGHEST GUST SPEED/DIRECTION    66/270    DATE  06/27

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR            6
NUMBER OF DAYS PC             22
NUMBER OF DAYS CLOUDY          2

AVERAGE RH (PERCENT)     47

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM             10     MIXED PRECIP               0
HEAVY RAIN                2     RAIN                       2
LIGHT RAIN                8     FREEZING RAIN              0
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                0     SNOW                       0
LIGHT SNOW                0     SLEET                      0
FOG                       3     FOG W/VIS <= 1/4 MILE      0
HAZE                      1

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.

July weather preview: Hot temps, storms typically the highlight

Change is of course the one constant in Denver’s weather but come July, things actually get pretty consistent.

The standard formula for a day in July is a sunny morning, clouds developing in the late morning and early afternoon. Come mid-afternoon, thunderstorms are rolling off of the foothills and into the metro area and the eastern plains. These storms do occasionally reach severe status containing hail, gusty winds and heavy downpours of rain.

Check out our July weather preview for a complete look at what is in store for the month ahead.

Record high temperature set for June 20

Record High TemperaturesWe knew it would be hot today and the proof is in the numbers as Denver set a new record high temperature for the date.

According to the National Weather Service, the mercury topped out at 99 degrees at Denver International Airport.  This breaks the previous record high for June 20 of 97 degrees set in 2007.

Here in Thornton, we almost matched the record with a high of 97.9 degrees at 3:57pm.

There will be no break from the heat until Friday.

Tomorrow’s forecast high of 98 degrees mirrors today’s high and will again come close to the record for June 21 (99 degrees in 2007). Thursday does cool some but with a forecast high of 91 degrees, the reading will still be well above normal for the date (85 degrees).

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Summer solstice ushers in astronomical summer, longest day of the year

On the June solstice, the Earth’s northern hemisphere is tilted at its maximum toward the sun. The result is the longest day of the year for the northern part of the planet. (NASA)
On the June solstice, the Earth’s northern hemisphere is tilted at its maximum toward the sun. The result is the longest day of the year for the northern part of the planet. (NASA)

Astronomical summer arrives in Thornton tonight and with the solstice we will enjoy our longest day of the year.

Summer officially begins at 10:24pm MDT tonight.  The Summer Solstice occurs when the North Pole is tilted at it closest to the sun – 23.4 degrees.  This results in the longest day of the year in the Northern Hemisphere.

Here in Denver the sun rises at 5:32am today and sets at 8:31pm.  This will give us 14 hours, 59 minutes and 14 seconds of daytime.  Tomorrow it will be a bit less than one second shorter than today and each day from now through the Winter Solstice in December will get gradually shorter as well.

At the poles of the globe, the seasonal extremes will be quite notable.  Areas north of the Arctic Circle to the North Pole will see 24 hours of daylight and have a midnight sun.  On the opposite end of the globe, the South Pole will have no direct sunlight at all as they are in the depths of their winter.

Did you know that there is a difference between the astronomical seasons that we are discussing here and meteorological seasons?

Meteorological seasons differ slightly and are geared toward matching the calendar with the annual temperature cycle. This is done primarily for meteorological observing and forecasting and in many ways it is more logical than the astronomical seasons.

For the Northern Hemisphere, the meteorological spring covers the months of March, April and May. Summer brings the hottest months of the year and so meteorological summer is June, July and August. Meteorological fall then is September, October and November followed by the coldest months of December, January and February as meteorological winter.

Thornton’s June weather preview: Hotter temps, more severe weather the norm

Thornton's June weather preview.Extreme weather can occur during in month in Colorado we well know.  June however is when traditional spring severe weather arrives in the state oftentimes with hail, damaging wind and tornadoes.

Over 40 percent of the tornadoes that occur in Colorado happen during the month of June.  Far more common are thunderstorms with hail and wind, each responsible for extensive damage each year.

While severe weather is common, so too are brilliantly sunny and mild days as we close out spring and enter summer.  If you are looking for cold, it isn’t likely but it is possible as the Denver area has seen freezing temperatures and yes, even snow, during the month.

Read more about Thornton and Denver’s June weather and a look ahead at this year.