Boulder Weather Summary for 2007
Steve Jones and George Oetzel
Despite a frigid and snowy beginning and ending, 2007 was the fourth consecutive warmer-than-average year in Boulder. The mean daily temperature was 0.7° F above average, and 8 of the 12 months were warmer than average. So far this decade, Boulder's mean daily temperature is running 0.6° F above the 110-year average.
Boulder received 16.9" of precipitation during 2007, about 2" below the 110-year average of 19". For the decade, Boulder has averaged 18.9" of precipitation per year. Boulder received 86" of snow in 2007, about 6" above the long-term average. Roughly 70% of this snow fell during January and December, usually our driest months. Boulder's annual snowfall this decade has averaged 82".
It’s worth noting that Boulder's current recording station at the National Institute of Standards may be in a slightly wetter and cooler location than some of the previous recording stations. If we limit ourselves to the 18 years that weather observations have been taken at NIST, 2007 was about 4" drier and 5" less snowy than average. However, those 18 years do encompass the exceptionally wet 1990s. In other words, given the inconsistencies in Boulder weather recording, "average" is a moving target.
Here's a month-by-month summary of 2007, with mean daily temperature departure from average in parentheses. December data are unofficial:
January: Cold and snowy. High 62, Low -4 (-5.1°), 1.68", 29" snow
February: Snowy. High 67, Low -13 (-0.1°), 0.86", 14" snow
March: Exceptionally warm. High 75, Low 12 (+7.6°), 1.69", 5" snow
April: Cool. High 82, Low 21 (-2.4°), 2.24", 2" snow
May: Dry. High 82, Low 32 (+0.6°) 1.79"
June: Dry. High 97, Low 34 (+0.7°), 0.38"
July: Warm and dry. High 98, Low 52 (+2.7°), 0.80"
August: Warm. High 97, Low 48 (+2.1°), 1.82"
September: Warm and wet. High 90, Low 38 (+2.3°), 1.92"
October: Warm. High 83, Low 25 (+2.5°), 1.38"
November: Very warm and dry. High 76, Low 12 (+3.5°), 0.47", 6" snow
December: Cold and snowy. High 65, Low 3 (-6.0°), 1.85", 30" snow
The graphs below show how the monthly means compare with past years and with averages. Weather recording was on the grounds of the Boulder Central Fire Station, north of downtown, from 1958 to 1989. There was no recording station from 8/1/89 through 3/31/90. Beginning 4/1/90, the current station on the NIST campus was established. Correspondingly, the graphs use different symbols for the two periods, and there are two lines that reflect the averages.
January has a generally increasing trend since the NIST station was established, but 2007 was the coldest during that time. July also shows an increasing trend through the 90's, with signs of a turnaround in the next decade. Of course, these trends should not be regarded as indicators of the effect in Boulder of global warming. Eighteen years is much too short an interval to provide evidence of a long-term trend.
Drought Update: Throughout the first seven years of this decade, Boulder reported near-average precipitation, while most reporting stations in eastern Colorado and adjacent states reported below-average precipitation. That trend reversed itself in 2007. Here are 2007 percent of average precipitation amounts for selected regional stations: Boulder 89, DIA 110, Alamosa 158, Grand Junction 140, Pueblo 110, Albuquerque 112, Casper 125, Cheyenne 102, Scottsbluff 65, North Platte 138, Goodland 88.
| The adjacent figure shows Boulder's annual precipitration for the period 1961 through 2007. As in the above figures, the two horizontal lines represent averages for the periods of the two different measuring stations. It is likely that the NISTstation would have recorded more precipitation than the downtown station if they had operated in the same years, because it is closer to the uplift of the Flatirons. The graph shows that the decade of the '90s was generally wetter than average, while the current decade has seen more dry than wet years.
Data for the graphs are from NOAA's Boulder Web pages.
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