National Weather Service United States Department of Commerce

Heavy Rainfall for Portions of Coastal Texas; Fire Weather Concerns for Alaska

A tropical disturbance off the Texas coast will bring the threat for some heavy rainfall through Friday. Meanwhile, monsoonal moisture flows into the Southwest and southern Rockies where flash flood threat will increase. Severe thunderstorms are expected across the Upper Midwest and western Great Lakes today. Dry and warm conditions for interior Alaska as fire weather concerns continue. Read More >

        ...A STATISTICAL PREVIEW OF DENVER'S JULY WEATHER...

 

JULY IS DENVER'S CLIMATOLOGICAL WARMEST MONTH OF THE YEAR AND LIKE MOST LOCATIONS IN THE UNITED STATES, THE DAILY AVERAGE TEMPERATURES PEAK APPROXIMATELY 4 WEEKS AFTER THE SUMMER SOLSTICE. DENVER, ALONG WITH THE ENTIRE SPAN OF THE U.S. ROCKIES, EXPERIENCE THE ONSET OF THE NORTH AMERICAN MONSOON DURING JULY. NEARLY EVERY YEAR, A DOMINANT RIDGE OF HIGH PRESSURE TYPICALLY DEVELOPS OVER THE CENTRAL UNITED STATES WITH COLORADO LOCATED ON THE WESTERN EDGE. THIS ALLOWS FOR SUBTROPICAL MOISTURE TO DRAW NORTHWARD AT ALL LEVELS OF THE ATMOSPHERE AND INTO THE ROCKY MOUNTAIN REGION.

 

LIKE JUNE, LOW LEVEL GULF MOISTURE OFTEN FINDS IT'S WAY INTO EASTERN COLORADO ON THE WESTERN EDGE OF THE CENTRAL UNITED STATES LOW-LEVEL JET. THE WEAKEST OF UPPER LEVEL DISTURBANCES IN WEST TO NORTHWESTERLY FLOW ALOFT, RIDING OVER THE MOISTURE AT THE LOW LEVELS, CAN IGNITE AN AFTERNOON AND EVENING OF SEVERE WEATHER RANGING FROM HEAVY RAIN TO TENNIS BALL SIZED HAIL TO TORNADOES.

 

WITH DENVER'S DAILY NORMAL TEMPERATURES PEAKING IN LATE JULY, TEMPERATURE VARIATION BECOMES FAIRLY LOW FROM THE BEGINNING THROUGH THE END OF THE MONTH. DENVER'S MONTHLY MEAN TEMPERATURE FOR JUNE IS 74.2 DEGREES (1981-2010 AVERAGES) AND IS DENVER'S WARMEST MONTH OF THE YEAR. JULY STARTS THE MONTH WITH A NORMAL HIGH OF 87 DEGREES AND ENDS WITH A NORMAL HIGH OF 90 DEGREES. FOR LOW TEMPERATURES, THE MONTH BEGINS WITH A NORMAL OF 57 DEGREES AND FINISHES WITH A NORMAL OF 60.

 

THE WARMEST TEMPERATURE EVER RECORDED DURING THE MONTH OF JULY, SINCE RECORDS BEGAN IN 1872, WAS 105 DEGREES ON THE 20TH DAY OF 2005. JULY'S COLDEST TEMPERATURE EVER RECORDED IN DENVER WAS 42 DEGREES AND OCCURRED ON THE 31ST DAY OF 1873.

 

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

 

78.9 DEGREES 2012 *** WARMEST MONTH IN DENVER HISTORY FROM 1872-2011

77.8         1934

77.7         2005

77.6         2008

77.3         1936

77.1         1939

76.9         2003

76.9         1966

76.7         2001

76.7         2000

 

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

 

67.4 DEGREES 1895

68.2         1906

68.7         1915

68.7         1904

68.9         1950

68.9         1905

68.9         1891

69.0         1875

69.1         1967

69.1         1872

 

ALONG WITH JUNE, THE POSSIBILITY OF SEVERE WEATHER IN FULL FORCE DURING THE MONTH OF JULY. RAINFALL TOTALS FROM STRONG, RAIN DUMPING THUNDERSTORMS ARE STILL THE MEASURE OF INTEREST. DENVER'S THE 3RD AND 5TH WETTEST MONTHS IN DENVER HISTORY OCCURRED IN JULY, 1965 AND JULY 1998, RESPECTIVELY. THE 8TH HIGHEST 24 HOUR PRECIPITATION TOTAL IN DENVER HISTORY OCCURRED ON JULY 30TH, 1997 AS 2.17 INCHES OF RAIN FELL.

 

JULY: DENVER'S WETTEST

 

6.41 INCHES 1965

5.92        1998

5.60        1997

5.24        1919

4.76        2001

4.28        1895

4.17        1965

4.17        1909

4.17        1875

4.11        1991

 

JULY: DENVER'S DRIEST

 

0.01 INCHES 1901

0.08        1939

0.24        2008

0.27        2005

0.31        1917

0.32        1934

0.33        1924

0.33        1877

0.34        1891

0.41        1888

 

 

                    ...THE OUTLOOK FOR JULY 2015...

 

AFTER A JUNE 2015 WITH ABOVE NORMAL PRECIPITATION AND ABOVE NORMAL TEMPERATURES, THE SHORT TO MEDIUM RANGE MODELS INDICATE A DOMINANT STABLE RIDGE OF HIGH PRESSURE OVER THE SOUTHERN AND CENTRAL ROCKIES. THIS WILL TEND TO KEEP TEMPERATURES NEAR TO ABOVE AVERAGE THROUGH THE FIRST 7-10 DAYS OF JLUY WITH PRECIPITATION NEAR TO BELOW NORMAL. FOR THE REMAINING TWO THIRDS OF THE MONTH THE LONG RANGE CLIMATE MODELS POINT TOWARD A PATTERN OF NEAR TO BELOW NORMAL TEMPERATURES WITH A SLIGHTLY BETTER CHANCE FOR ABOVE NORMAL PRECIPITATION. THIS ABOVE NORMAL PRECIPITATION COULD BE AN INDICATION OF THE ONSET OF THE NORTH AMERICAN MONSOON, WHICH TYPICALLY PEAKS IN LATE JULY AND INTO EARLY AUGUST.

 

 

                       ...JULY STATISTICS...

 

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

 

AVERAGE HIGH...........................  89.4

AVERAGE LOW............................  58.9

MONTHLY MEAN...........................  74.2

DAYS WITH HIGH 90 OR ABOVE.............  16 (16.0)

DAYS WITH HIGH 32 OR BELOW.............   0 (0.0)

DAYS WITH LOW 32 OR BELOW..............   0 (0.0)

DAYS WITH LOWS ZERO OR BELOW...........   0 (0.0)

 

...PRECIPITATION...

 

MONTHLY MEAN...........................   2.16 INCHES

DAYS WITH MEASURABLE PRECIPITATION.....   8 (8.3)

AVERAGE SNOWFALL.......................   0.0 INCHES

 

...MISCELLANEOUS JULY AVERAGES...

 

HEATING DEGREE DAYS....................   6

COOLING DEGREE DAYS.................... 289

WIND SPEED (MPH).......................   8.3*

WIND DIRECTION......................... SOUTH*

DAYS WITH THUNDERSTORMS................  11* (11.1)

DAYS WITH DENSE FOG....................   0* (<0.4)

PERCENT OF SUNSHINE....................  71*

(NOTE: SUNSHINE DATA ARE NO LONGER COLLECTED AS OF OCTOBER 1, 2009)

 

* = 1971-2002 NORMALS

 

...JULY EXTREMES...

 

RECORD HIGH............................ 105 DEGREES ON 7/20/2005

RECORD LOW.............................  42 DEGREES ON 7/4/1903

                                                       7/31/1873

WARMEST JULY...........................  78.9* DEGREES IN 2012

                                               *WARMEST MONTH IN

                                                DENVER HISTORY

MAXIMUM COOLING DEGREE DAYS............ 438 IN 2012

MINIMUM COOLING DEGREE DAYS............ 181 IN 2009

COLDEST................................  67.4 DEGREES IN 1895

MAXIMUM HEATING DEGREE DAYS............  42 IN 1951

MINIMUM HEATING DEGREE DAYS............   0 NUMEROUS YEARS

WETTEST................................   6.41 INCHES IN 1965

DRIEST.................................   0.01 IN 1901

 

WFO BOULDER