Notable June heat waves for the DMV

 

DC's 7-day forecast (Photo Credit: WUSA9)

Today is the second day of what could ultimately end up being a heat wave spanning a week or more in the nation's capital. Over the last 30 years there have been only three such heat waves in the nation's capital to occur exclusively during the month of June. A "heat wave" is loosely defined as a minimum of three consecutive days of 90° heat or greater.

2010:  The signature weather event of DC's warmest June on record was an 11-day heat wave from June 19 - 29. Seven of those 11 days had high temperatures of at least 95°, including a record high of 100° on June 24. That was also DC’s first instance of triple-digit June heat since 1997. 

While more than a decade had passed since the last time Washingtonians experienced triple-digit June heat, June 2010 was the first of three consecutive June’s with 100° heat. This June finished with 18 days of 90-degree heat compared to DC's June average of between seven and eight such days.

1997: Unlike June 2010, the first 17 days of June in 1997 were cooler than average in the nation's capital. That includes a June 3 record cool high of 58°, which is DC's average high on March 20. However, a major shift in the weather pattern occurred during the second half of the month. That led to a nine-day heat wave from June 20 – 28. The hottest day was June 25 that featured a record high of 100°.

Although 9 of the final 13 days of this June were warmer than average, it still finished 3.2° cooler than average in the nation's capital. That helps underscore how a heat wave, irrespective of how significant it may be, isn't always enough to offset unusually cooler weather over the course of an entire month.

1994: For nearly two decades, June 1994 held the distinction of DC’s hottest on record. It also featured the hottest weather of the summer with a 14-day streak of 90° heat from June 13 – 26.  The hottest day was June 15 with a record high temperature of 101°. A total of five record highs were set during the month, including three consecutive records from June 14 – 16 that all still stand today, 30 years later. According to NOAA, no June has had more than one day of 100° heat in the nation’s capital.

Although June 2010 bumped June 1994 to DC's second warmest, the 11-day heat wave from 2010 and 14-day heat wave from 1994 have similarities given their duration and intensity. Both last more than 10 days and included triple-digit heat. However, the June 2010 heat wave was slightly more intense in the nation's capital with an average daily high/low temperature of 95.4°/74.7° from June 19 - 29.  That's compared to DC's average high/low temperature of 94.7°/73° from June 13 - 26, 1994.