As temperatures start to drop, September 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.
However that isn’t to say the weather can’t be a lot more “interesting.” Extremes can occur during September ranging from heat to cold to yes, even snow.
From the National Oceanic & Atmospheric Administration: The combined global land and ocean surface temperature made this July the second warmest on record, behind 1998, and the warmest averaged January-July on record. The global average land surface temperature for July and January–July was warmest on record. The global ocean surface temperature for July was the fifth warmest, and for January–July 2010 was the second warmest on record, behind 1998.
The monthly analysis from NOAA’s National Climatic Data Center, which is based on records going back to 1880, is part of the suite of climate services NOAA provides government, business and community leaders so they can make informed decisions.
Global temperature anomolies, July 2010. (NOAA)
Global Temperature Highlights
The combined global land and ocean average surface temperature for July 2010 was the second warmest on record at 61.6°F (16.5°C), which is 1.19°F (0.66°C) above the 20th century average of 60.4°F (15.8°C). The averaged temperature for July 1998 was 61.7°F (16.5°C).
The July worldwide land surface temperature was 1.85°F (1.03°C) above the 20th century average of 57.8°F (14.3°C) — the warmest July on record. Warmer-than-average conditions dominated land areas of the globe. The most prominent warmth was in Europe, western Russia and eastern Asia. Cooler-than-average regions included central Russia, Alaska and southern South America.
According to the Finnish Meteorological Institute, Finland set a new all-time maximum temperature on July 29 when temperatures soared to 99.0°F (37.2°C), surpassing the previous record set in July 1914 by 2.3°F (1.3°C).
Western Russia was engulfed by a severe heat wave during much of July. On July 30, Moscow set a new all-time temperature record when temperatures reached 102°F (39°C), exceeding the previous record of 99.0°F (37.2°C) set four days earlier. Before 2010, the highest maximum temperature recorded in Moscow was 98.2°F (36.8°C), set nine decades ago.
According to the Beijing Climate Center, the July 2010 average temperature across China was 73.0°F (22.8°C), which is 2.5°F (1.4°C) above the 1971-2000 average and the warmest July since 1961.
The worldwide ocean surface temperature was 0.97°F (0.54°C) above the 20th century average of 61.5°F (16.4°C) and the fifth warmest July on record. The warmth was most pronounced in the Atlantic Ocean.
La Niña conditions developed during July 2010, as sea surface temperatures (SST) continued to drop across the central and eastern equatorial Pacific Ocean. According to NOAA’s Climate Prediction Center, La Niña is expected to strengthen and last through the Northern Hemisphere winter 2010-2011.
For the year-to-date, the global combined land and ocean surface temperature of 58.1°F (14.5°C) was the warmest January-July period on record. This value is 1.22°F (0.68°C) above the 20th century average.
Global temperature anomolies, January through July, 2010. (NOAA)
Polar Sea Ice and Precipitation Highlights
Arctic sea ice covered an average of 3.2 million square miles (8.4 million square kilometers) during July. This is 16.9 percent below the 1979-2000 average extent and the second lowest July extent since records began in 1979. The record low July was set in 2007. This was the 14th consecutive July with below-average Arctic sea ice extent. July 1996 was the last year that had above-average sea ice extent.
Antarctic sea ice extent in July was above average, 4.8 percent above the 1979-2000 average—resulting in the largest July sea ice extent on record.
According to Australia’s Bureau of Meteorology, the continent received an average of 34.4 mm (1.35 inches) of precipitation during July 2010—this is 55 percent above the 1961-1990 average and the highest value since 1998.
Scientists, researchers and leaders in government and industry use NOAA’s monthly reports to help track trends and other changes in the world’s climate. This climate service has a wide range of practical uses, from helping farmers know what and when to plant, to guiding resource managers with critical decisions about water, energy and other vital assets.
Denver and Thornton's August weather preview and history.
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.
At the start of the month Denver usually averages around 88 degrees for a high temperature. By the end of August that drops to 82 degrees. Similarly, nighttime lows drop from 60 to 53 from the start to the end of the month.
Generally clear skies can be expected between midnight and noon but the afternoon often brings showers and thunderstorms. These storms typically develop over the foothills then bring precipitation to the Denver metro area.
According to the National Weather Service, record-setting rain fell in Denver on the 4th of July. But is it accurate to say that? (ThorntonWeather.com)
Heavy rain showers put a damper on a lot of Independence Day celebrations yesterday. Thunderstorms moved across the Front Range dumping rain and hail across northeastern Colorado with enough rain falling to set a record for the 4th of July.
At Denver International Airport (DIA), 1.84 inches of rain was recorded. This easily eclipses the old 4th of July record dating back to 1909 when 1.44 inches fell.
Here in Thornton we weren’t nearly as wet having recorded 0.81 inches for the storms that moved through. Some of the other rainfall totals from across the metro area:
The rain yesterday was heavy in places but nowhere in the central Denver area measured anywhere near the amount DIA recorded (see map below). When the National Weather Service (NWS) announces a “record” like the rain yesterday, it is comparing the measurements at DIA to historical records taken at the old Stapleton International Airport from 1950 to 1995 and downtown from 1871 to 1949.
Is it accurate to claim a weather record when the station doing the recording is 12 miles away from where historical records were made? Of course not and this is a problem.
The National Weather Service either needs to start recording Denver’s official statistics from the new station or it needs to quit comparing data from DIA to that recorded before the move in 1995.
Denver’s climate records are forever being altered and the public is being misled.
June typically brings severe weather to Thornton and the Denver area.
June is historically Denver’s severe weather month and severe thunderstorms, tornadoes and hail are notorious visitors to Denver and across eastern Colorado during the month. In fact, over 40 percent of the tornadoes that occur in Colorado are observed in June and these are typically the most destructive of the year. Severe thunderstorms have also caused major property damage across the Front Range during the month.
In just the last 25 years or so, there have been some particularly notable storms in June. Tornadoes have struck the metro area including one that longtime Thornton residents will recall on June 3, 1981. 53 residents were injured, 25 homes were destroyed and 239 other structures were damaged. Others tornadoes in the metro area include southeast Denver and Aurora on June 8, 1986 and east Denver on June 13, 1984. Severe thunderstorms occurring on June 13, 1984 dumped large hail making it one of the worst and the second costliest storm in Denver history. More recently, on June 20, 2001, a major hail storm moved across Denver International Airport dropping hailstones as big as two inches in diameter. Damage was extensive on and near the airport.
According to data released by the National Oceanic and Atmospheric Administration (NOAA), the combined land and sea temperatures for last month were the warmest April temperatures on record. Individually, sea surface temperatures were the warmest for any April and surface temperatures were the third warmest.
Utilizing data from the National Climatic Data Center (NCDC), the agency reported that the combined temperature of 58.1°F (14.5°C) was 1.37°F (0.76°C) above the 20th century average of 56.7°F (13.7°C).
For the period from January to April, temperatures also were the warmest first quarter on record. NOAA said the combined temperature over the period was 56.0°F (13.3°C). That is 1.24°F (0.69°C) above the 20th century average.
In the United States, NOAA said that April featured above normal temperatures and below normal precipitation. Much of the eastern half of the nation experienced warmer than normal temperatures resulting in measurements 2.3°F above average and going down in the books as the 14th warmest April on record.
Colorado natives and those that have lived here long enough know that Denver and Colorado weather changes considerably throughout the year. The month of May almost seems to pack four seasons of weather conditions into 31 days. You name it, it can happen.
This being the latter half of spring, May does mean warm temperatures. Temperatures in the 80’s are common and reaching into the 90’s is not unheard of. The normal highs start out at 65 on the first but by the end of the month that climbs to 76. The record high for the month was recorded on May 26, 1942 of 95 degrees.
Despite the snowstorm that struck on March 23rd and 24th and the rain that fell beforehand, the National Weather Service says Denver's March precipitation was below normal.
According to the Denver / Boulder office of the National Weather Service, Denver’s March weather was warmer and drier than normal. The latest climate summary from the service would seem to contradict what Denver residents actually experienced, at least in terms of precipitation.
The report starts with a seemingly contradictory statement saying, “Denver’s March 2010 finished with below normal liquid moisture in spite of finishing above normal in the snowfall category.”
According to the report, Denver recorded 0.80 inch of precipitation, well below the normal of 1.28 inches. Most of that occurred in conjunction with the snowstorm on the 23rd of the month when the official measuring station at Denver International Airport (DIA) reported 0.61 inch of precipitation. By contrast, ThorntonWeather.com recorded 1.42 inches of precipitation from that storm alone and 1.90 inches for the month.
Overall for the season, Denver has recorded 58.8 inches of snow which is 7.5 inches above the average snowfall up to this point. Denver’s snow season runs from July through June and we average 61.7 inches over that period so for 2010 we are quickly approaching a ‘normal’ year.
The average temperature as recorded at DIA was 41.0 degrees which was 1.4 degrees above the normal of 39.6 degrees. Temperatures for the month ranged from a high of 82 degrees on the 30th down to a low of 13 degrees on the 20th. The 82 degree high temperature on the 30th broke the record for that date of 81 degrees set way back in 1879.
Controversy once again surrounds measurements in latest report
The March 2010 climate summary once again highlights the problem. Comparison of temperature records for DIA versus areas closer to historical monitoring locations continue to show discrepancies. Standing out even more are precipitation records that are curious at best, ridiculous at worst given the wet snowstorm that struck on the 23rd and 24th.
The Denver Weather Examiner is in the process of updating our previous investigation and will have an updated report soon. In the meantime, you may wish to look at the results of the investigation we conducted last year.
April marks a transition between winter and summer for most of the country but for Denver it is especially true as we can see a stunning variety of weather. The proverbial April showers are certainly a possibility for Denver. Snow? Tornadoes? Thunderstorms? You bet – all can happen! For good measure throw in a chance for hail and even dust storms and April gives every type of weather condition you could like – or hate.
The good news is that sunshine and warmer temperatures are usually in abundance as the normal highs during the month move up from 57 degrees on the first to 65 degrees on the 30th. It is not unusual to have a number of days well into the 70’s and the low 80’s. We also see the normal lows move above freezing from 30 degrees at the start of the month to 39 degrees by the end. Temperature extremes can hit both ends of the spectrum with a record low of 2 degrees below zero on April 2, 1975 and a record high of 90 degrees on April 30, 1992.
March in Denver typically means frequent and rapid weather changes. The days grow longer and we start enjoying more sunshine and sometimes summer-like weather. However, on occasion arctic air masses can still force their way south into Colorado dropping temperatures quickly and markedly.
These changes are due to March’s “in between” status – elements during the month have much in common with winter and spring. In addition to arctic fronts, Pacific storms frequently move across Colorado from the west and warm moist air streams up from the Gulf of Mexico northeastward into the state. When these cold fronts collide with the warmer air masses the result can be some crazy weather.
As temperatures start to drop, September 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.
