Notwithstanding last month’s tornadoes in Windsor and the northern Front Range, June is historically Denver’s real severe weather month.  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.

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 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.

Looking Back at June 2007  - Five weather records set or tied

June 2007 finished 1.2 degrees above normal in the temperature department. Temperatures ranged from a record setting 100 degree reading on the 24th down to a record low temperature of 31 degrees on the 8th – quite a contrast!  Those official measurements though were not reflected on our side of town as we recorded a high of 98.7 and a low of 37.8.  The official measurement of one hundred degrees on the 24th was the first of the year and the first triple digit temperature since June 14, 2006.  At the other end of the thermometer, the 31 degree low temperature record became the latest below freezing temperature in Denver weather history. 

On the 17th, a record high temperature was established breaking the old record of 94 last set in 1940 (in Thornton we recorded 94.3).  On the 20th we tied the record high of 97 last set in 1968. On the 21st a new record high of 99 degrees was set breaking the old record of 98 last set in 1922.  In all, there were 13 days where the mercury soared into the 90s (11 in Thornton), one day with a 100 degree reading and one temperature registered a below freezing temperature (31 degrees).

The monthly average temperature of 68.8 (69.1 in Thornton) was not even close enough to get into a top 10 category. Precipitation fell short of normal as only 0.52 inch was collected in the rain bucket as compared to a normal of 1.56 inches.  We were drier in Thornton with a mere 0.24 inch recorded.  Most of the rain fell on the 12th registering 0.46 inch in a 24 hour period (0.24 in Thornton). Two other days recorded measurable moisture and two days measured trace amounts.  Despite the relative dryness, June 2007 did not qualify for the top ten driest Denver months.  In 10th place was 0.21 inch recorded in 1990. Greatest June rainfall was 4.96 inches recorded in 1882.
Nine thunderstorms were observed during the month but no hail was recorded during Denver's 2007 severe weather month. 

The outlook for June 2008

The National Weather Service 30-day outlook models do not favor any particular meteorological models and therefore climatological normals are suggested for planning purposes.

For More Information

Temperature Normals and Extremes for June

Monthly Temperature, Rainfall and Snowfall Extremes for June

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