A Statistical Preview of Denver's May Weather

...A STATISTICAL PREVIEW OF DENVER’S MAY WEATHER...

JUST ABOUT ANYTHING CAN HAPPEN IN THE MONTH OF MAY WHEN IT COMES TO
DENVER'S WEATHER. ALTHOUGH MAY IS TYPICALLY KNOWN FOR IT'S WETTING RAINS, IT CAN ALSO BRING HEAT INTO THE 90'S, COLD DOWN TO THE 20'S, SEVERAL INCHES OF SNOW, AND

CERTAINLY THE BEGINNING OF THE SEVERE WEATHER SEASON. THE WETTEST MONTH IN DENVER HISTORY BROUGHT 8.57 INCHES OF PRECIPITATION IN 1876.

MUCH LIKE APRIL, FAST CHANGING WEATHER IS COMMON IN MAY OVER THE DENVER METRO AREA AND EASTERN PLAINS. AS COLD FRONTS OCCASIONALLY CLASH WITH WARM AND MOIST GULF

MOISTURE, SEVERE WEATHER TYPICALLY ENSUES AS GOOD DAYTIME HEATING PROVIDES GOOD SURFACE INSTABILITY.

DENVER'S MONTHLY MEAN TEMPERATURE FOR MAY IS 57.1 DEGREES (1981-2010 AVERAGES) AND IS DENVER'S 5TH WARMEST MONTH OF THE YEAR BEHIND JULY, AUGUST, JUNE AND SEPTEMBER

RESPECTIVELY. MAY STARTS THE MONTH WITH A NORMAL HIGH OF 66 DEGREES AND ENDS WITH A NORMAL HIGH OF 77 DEGREES. FOR LOW TEMPERATURES, THE MONTH BEGINS WITH A NORMAL

OF 38 DEGREES AND FINISHES WITH A NORMAL OF 48.

THE WARMEST TEMPERATURE EVER RECORDED DURING THE MONTH OF MAY, SINCE RECORDS BEGAN IN 1872, WAS 95 DEGREES ON THE 26TH DAY OF 1942. MAY'S COLDEST TEMPERATURE EVER

RECORDED IN DENVER WAS 19 DEGREES AND OCCURRED ON THE 3RD DAY OF 1907.

MAY: DENVER'S TOP 10 COLDEST (MEAN TEMPERATURES):

48.7 DEGREES 1917
50.0         1995
50.1         1935
50.3         1907
51.4         1983
51.5         1892
52.0         1946
52.6         1967
52.7         1924
52.8         1943

MAY: DENVER'S TOP 10 WARMEST (MEAN TEMPERATURES):

64.7 DEGREES 1934
63.2         1994
62.0         1886
61.7         1958
61.6         1974
61.6         1879
61.5         1939
61.3         1936
61.1         1875
61.1         1941

FOR DENVER'S NINE MONTH SNOW PERIOD OF SEPTEMBER THROUGH MAY, MAY RANKS AS THE LEAST SNOWIEST MONTH AND ONLY ACCOUNTS FOR APPROXIMATELY 2 PERCENT OF THE ANNUAL

SNOWFALL OF 53.8 INCHES. DENVER NORMALLY COLLECTS 1.1 INCHES OF SNOW IN MAY BASED ON AVERAGES FROM FORMER STAPLETON INTL AIRPORT (1981-2010 AVERAGES). AT LOWER

ELEVATIONS, INCLUDING THE EASTERN PLAINS, FRONT RANGE AND METRO DENVER, MAY STORMS TYPICALLY BRING RAIN. SNOW IN MAY WILL OFTEN OCCUR IN THE OVERNIGHT AND EARLY

MORNING PERIODS WHEN THE DAILY TEMPERATURES ARE THE COLDEST.

MAY: DENVER'S TOP 10 SNOWIEST

15.5 INCHES 1898
13.7        1950
13.5        1978
13.2        1921
12.0        1917
10.0        1908
 9.0        1907
 8.9        1893
 8.8        1957
 8.3        1944

THE END OF THE WINTER AND ONSET OF SPRING ALONG THE FRONT RANGE AND HIGH PLAINS OCCASIONALLY EXPERIENCE EXTENDED DROUGHT-LIKE CONDITIONS. THESE DRY PERIODS ARE

OFTEN ASSOCIATED WITH LA NINA PHASES OF THE PACIFIC OCEANIC REGION. LIKE MARCH AND APRIL, THE DRIEST MAYS USUALLY START THE MONTH WITH ABOVE NORMAL MONTHLY

TEMPERATURES MAINLY DUE TO WINDY, CLOUD FREE, DOWNSLOPE WINDY DAYS COMBINED WITH WARMER NIGHT-TIME LOW TEMPERATURES.

MAY: DENVER'S LEAST SNOWY

NUMEROUS YEARS WITH NO SNOWFALL (43)

MAY CAN ALSO BE CONSIDERED THE FIRST MONTH OF THE SEVERE WEATHER AND THUNDERSTORM SEASON IN THE DENVER AREA. TROUGHS OF LOW PRESSURE OFTEN USHER IN RELATIVELY COLD

AIR ALOFT IN NORTHWEST FLOW. THIS CAN CREATE PERIODS OF INSTABILITY IN COMBINATION WITH SURFACE AIRMASS COLLISIONS OF COLD AIR AND WARM MOIST GULF AIR. AS THE YEAR

MOVES INTO THE WARM AND CONVECTIVE MONTHS OF SPRING AND SUMMER, MONTHLY PRECIPITATION TOTALS BECOME A MEASURE OF INTEREST. AGAIN, AS NOTED ABOVE, DENVER'S WETTEST

MONTH IN HISTORY OCCURRED IN MAY OF 1876 AND BROUGHT 8.57 INCHES OF PRECIPITATION. THIS IS OVER HALF OF THE AVERAGE ANNUAL PRECIPITATION OF 14.92 INCHES.

MAY: DENVER'S TOP 10 WETTEST

8.57 INCHES 1876 *** WETTEST MONTH IN DENVER HISTORY
7.31        1957
6.12        1969
5.06        1973
4.95        1935
4.88        1938
4.88        1898
4.79        2011
4.77        1967
4.67        1995

MAY: DENVER'S TOP 10 DRIEST

0.06 INCHES 1974
0.09        1886
0.15        1899
0.22        1919
0.34        1977
0.34        1966
0.43        1925
0.49        1972
0.52        1911
0.53        1900

                    ...THE OUTLOOK FOR MAY 2015...

AFTER AN APRIL WHICH EXPERIENCED ABOVE NORMAL PRECIPITATION, NEAR  NORMAL SNOWFALL AND NEAR NORMAL TEMPERATURES, THE SHORT TO MEDIUM RANGE MODELS INDICATE A

CONTINUED UNSETTLED PATTERN FOR THE FIRST 10 DAYS OF MAY SUGGESTING SHOWER ACTIVITY AND POSSIBLY WETTING RAINS. FOR THE REMAINDER OF MAY 2015...THE CLIMATE

PREDICTION CENTER'S LONG RANGE MONTHLY FORECAST INDICATES NEAR NORMAL TEMPERATURES WITH A SLIGHT BIAS TOWARD ABOVE NORMAL WARMTH. AS FOR PRECIPITATION, THERE WILL

BE AN ABOVE NORMAL CHANCE FOR PRECIPITATION FOR THE REMAINDER OF MAY 2015.

                       ...MAY STATISTICS...

...TEMPERATURES (1981-2010 NORMALS)...

AVERAGE HIGH...........................  71.5
AVERAGE LOW............................  42.7
MONTHLY MEAN...........................  57.1
DAYS WITH HIGH 90 OR ABOVE.............   1  (0.8)
DAYS WITH HIGH 32 OR BELOW.............   0  (0.0)
DAYS WITH LOW 32 OR BELOW..............   2  (1.9)
DAYS WITH LOWS ZERO OR BELOW...........   0  (0.0)

...PRECIPITATION...

MONTHLY MEAN...........................   2.12 INCHES
DAYS WITH MEASURABLE PRECIPITATION.....   9  (9.4)
AVERAGE SNOWFALL........................  1.1 INCHES (9TH AND LEAST SNOWIEST MONTH)

...MISCELLANEOUS MAY AVERAGES...

HEATING DEGREE DAYS....................  265
COOLING DEGREE DAYS....................   21
WIND SPEED (MPH).......................    9.3*
WIND DIRECTION.........................  SOUTH*
DAYS WITH THUNDERSTORMS................    6* (6.4)
DAYS WITH DENSE FOG....................    1* (0.5)
PERCENT OF SUNSHINE....................   64*
(NOTE: SUNSHINE DATA ARE NO LONGER COLLECTED AS OF OCTOBER 1, 2009)

* = 1971-2002 NORMALS

...MAY EXTREMES...

RECORD HIGH............................  95 DEGREES ON 5/26/1942
RECORD LOW.............................  19 DEGREES ON 5/3/1907
WARMEST................................  64.6 DEGREES IN 1934
MAXIMUM COOLING DEGREE DAYS............  60 IN 1994
MINIMUM COOLING DEGREE DAYS............   0 1971, 1995
COLDEST................................  48.7 DEGREES IN 1917
MAXIMUM HEATING DEGREE DAYS............ 506 IN 1917
MINIMUM HEATING DEGREE DAYS............ 102 IN 1934
WETTEST................................   8.57 INCHES IN 1876
DRIEST.................................   0.06 INCHES IN 1974

WFO BOULDER