A Preview of Thornton's June Weather - The Severe Weather Month

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 30 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, 87 homes were destroyed and hundreds of other structures were damaged.  Other 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.

Despite the frequent tornadoes in June, due to the large areas of rural and unpopulated land there has never been a fatality in June due to a tornado.  Lightning on the other hand has caused several fatalities. 

Think we are done with the cold and snow now that June is here?  Most likely yes however cool weather can still occur early in the month.  The latest freeze on record in Denver occurred just last year on June 8, 2007 when the official low reached 31 degrees.  On June 2, 1951 the mercury dropped to 30 degrees –the record low temperature for June.  As for snow, June 11, 1947 actually saw a trace of snow fall! 

The wettest June was 1882 with 4.96 inches and the driest June was 1890 with only a trace of precipitation recorded. The maximum 24 hour precipitation was 3.16 inches on June 11, 1970 – that is a lot of rain for this area! 

Warmer temperatures are the norm though and by the end of the month temperatures can and have climbed above 100 degrees.  June 26, 1994 saw a record June temperature of 104 degrees.  Other dates with 100 degrees or higher include 102 on June 23rd 1954, June 27th 1990, June 29th 1990 and June 30th 1990 and 100 degrees set June 25th 1991.   The warmest June occurred in 1994 with an average temperature of 73.5 degrees. The coldest June was 60.6 degrees in 1967.

June 2003 was notable as it was the first June since 1972 with no 90 degree temperatures recorded. Just the year before, June 2002 had 17 90 degree days and June 2001 totaled out with 12 90 degree days.  On average June will have 6 days with above 90 degree temperatures. 

June 2006 saw us have one of the hottest June’s on record when the high temperature at the Denver International Airport reached into the nineties for 19 days.  This takes June 2006 into the record books with the most days having 90 degrees or above. The previous record for total number of 90 degree days for June was 17 occurrences established in 2002.  Also during June 2006, a record setting temperature of 102 degrees was recorded on the 14th of the month – the earliest June date that 100 degrees or higher was registered.  June 2006 was on track to become the Denver's warmest June but 3 days with highs in the 70s and several low temperature readings in the 40s and low 50s dropped the month into a tie as the 3rd warmest Denver June.

More recently, June 2009 brought an extraordinary amount of precipitation to the Denver area as 4.86 inches of rain was collected in the rain bucket. This was the second wettest June since 1872.

June Extremes

JUNE: Dever's Top 5 Coldest (mean temperatures):

60.6 degrees 1967
60.9 degrees 1951
61.0 degrees 1928
61.5 degrees 1969
61.6 degrees 1904

JUNE: Dever's Top 5 Warmest (mean temperatures):

75.0 degrees 2012
73.5 degrees 1994
73.4 degrees 1956
72.8 degrees 1933, 2006
72.6 degrees 1990

June: Denver's Snowiest

0.5 inches 1953
0.4 inches 1919
0.3 inches 1951
T inches 1917, 1937, 1947, 1974

June: Denver's Wettest

4.96 inches 1882
4.86 inches 2009
4.69 inches 1967
4.14 inches 1965
3.99 inches 2005

June: Denver's Driest

T inches 1890
0.08 inches 1916
0.09 inches 1881, 1980
0.12 inches 1952, 2006
0.13 inches 1893

The Outlook for June 2017

The Climate Prediction Center’s extended range forecast for June 2017 doesn’t lean heavily toward any overriding consideration. The agency gives Colorado equal chances of seeing above, below and at normal average temperatures for the month. In terms of precipitation, they do give the eastern part of the state a better than average chance of seeing above normal precipitation.

For More Information

Temperature Normals and Extremes for June

Monthly Temperature, Rainfall and Snowfall Extremes for June

JUNE AVERAGE STATISTICS * Normals & Means, 1981 - 2010
TEMPERATURE
AVERAGE HIGH	82.4
AVERAGE LOW	52.3
MONTHLY MEAN	67.4
DAYS WITH HIGH 90 OR ABOVE	8
DAYS WITH HIGH 32 OR BELOW	0
DAYS WITH LOW 32 OR BELOW	0
DAYS WITH LOWS ZERO OR BELOW	0
PRECIPITATION
MONTHLY MEAN	1.98 INCHES
DAYS WITH MEASURABLE PRECIPITATION	8
AVERAGE SNOWFALL	TRACE (Includes hail reports)
DAYS WITH 1.0 INCH OR MORE SNOWFALL	0
MISCELLANEOUS JUNE AVERAGES
HEATING DEGREE DAYS	62
COOLING DEGREES DAYS	133
WIND SPEED (MPH)	8.9 MPH
WIND DIRECTION	SOUTH
DAYS WITH THUNDERSTORMS	10
DAYS WITH DENSE FOG	0* (Less than 1)
PERCENT OF SUNSHINE POSSIBLE	70
JUNE EXTREMES
RECORD HIGH	104 ON 6/26/1994
RECORD LOW	30 ON 6/2/1951
WARMEST	73.5 IN 1994
COLDEST	60.6 IN 1967
WETTEST	4.96 INCHES IN 1882
MAXIMUM 24 HOUR MOISTURE	3.16 INCHES IN 1970
DRIEST	TRACE IN 1890
SNOWIEST (Could include hail)	0.4 INCH IN 1919 0.3 INCH IN 1951 TRACE IN 1974, 1947, 1937, 1917
LEAST SNOWIEST	0.0 INCH EXCEPT FOR THOSE YEARS LISTED ABOVE

* Historical weather statistics gathered from the National Weather Service's Denver / Boulder forecast office data archives.