Category Archives: Climatology

Climatology, Thornton Weather

Denver sets a new record high temperature for September 3

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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.

Climatology, Thornton Weather

Thornton’s September weather preview: A typically pleasant month

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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.

Climatology, Thornton Weather

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

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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.
Climatology, Thornton Weather

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

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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.

Climatology, Thornton Weather

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

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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.
Climatology

July weather preview: Hot temps, storms typically the highlight

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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.

Climatology

Record high temperature set for June 20

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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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Astronomy, Climatology

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

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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.

Climatology

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

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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.

Climatology

May 2017 weather recap: Month brings cooler, wetter than normal conditions

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The month of May 2017 brought a wide variety of conditions.  We experienced everything from summer-like temperatures to snow to severe weather with hail. In the end, average temperatures were below normal and precipitation more than double of average.

Between two systems at the start of the month, we began May with cool conditions and a bit of rain.  Drier and very warm conditions then arrived on the 5th through the 7th before we cooled down to near normal levels for a couple of days.

On the 8th of the month, severe weather paid its first visit of the season unleashing heavy rain and most notably, large hail. While Thornton was spared the damage, areas to the south and west were pummeled with hail nearly 3 inches in diameter. The storm goes into the books as the costliest hail storm in Colorado history.

Weather conditions then settled down for the next 10 days with temperatures varying from cool to quite warm.  On the 18th of the month, we then received a late season snowfall.  Thornton recorded 1.9 inches snow and a healthy 1.64 inches liquid precipitation from snow melt and rain.

The balance of the month was much quieter. Some days saw light rain with temperatures not straying too far from average for the most part.

Thornton’s overall average temperature for the month was 55.5 degrees.  This was a good ways below Denver’s long term average for the month of 57.1 degrees.  Out at DIA where Denver’s official measurements are kept, it was slightly warmer with an average of 55.9 degrees.

Temperatures saw a wide range during the month. Thornton’s warmest reading was 87.8 degrees on the 6th of the month.  Our coldest came in the wake of the snow on the 20th at 31.0 degrees. Denver saw its high of 86 degrees on the 6th as well and its low of 32 degrees on the 4th.

In terms of precipitation, Denver averages 2.12 inches during the month of May.  Both Thornton and Denver easily exceeded those marks.  Here in Thornton we recorded 4.84 inches of precipitation; in the Mile High City, 3.66 inches.

Snow in May is not unusual but getting it as late as we did is.  On average Denver records 1.1 inches during the month. In May 2017, Thornton saw 1.9 inches.  Out at the airport, a mere trace was recorded.

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

Thornton, Colorado's May 2017 temperature summary.
Thornton, Colorado’s May 2017 temperature summary.
Thornton, Colorado's May 2017 precipitation summary.
Thornton, Colorado’s May 2017 precipitation summary.