June offered a potpourri of weather in the Washington area with stretches of delightfully refreshing days and powerful punches of heat and humidity.

The average temperature worked out to 76.6 degrees, just 0.3 degrees warmer than the most recent 30-year average (1991 to 2020) and 0.4 degrees cooler than last year. It tied 1957 for the 23rd hottest June on record. Average monthly temperatures over the last five years have been tightly clustered, all within about one degree of each other.

June was wetter than normal with 5.51 inches in Washington, running 1.31 inches above the 1991 to 2020 average. This marks the 26th wettest June on record and keeps the year running on the wetter side.

The calendar graphic, below, helps to visualize the June 2021 twists and turns for Washington with the blue days marking the cooler-than-normal outcomes. It also displays the 12 days with measurable rainfall.

Extremes

The hottest June temperature for Washington was Wednesday’s 95-degree high, and the coolest reading was only a week before that with a refreshing low of 57.

The warmest low temperature of 76 degrees occurred on six separate instances, coinciding with our two heat waves between June 7 and 9 and June 28 and 30.

Records set during June concentrated at Dulles Airport, which has a shorter observation period (dating to the early 1960s) than Washington and Baltimore (dating to the late 1800s):

  • On June 5, Dulles set a record high of 92, breaking the prior record of 90 from 2002.
  • On June 6, Dulles set a record high of 93, breaking the prior record of 92 from 2005.
  • On June 7, Washington set a record warm low of 76 degrees, topping 74 from 2008.
  • On June 14, Dulles set a rainfall record of 1.02 inches, exceeding 0.91 inches from 1989.

The pattern

The June jet stream pattern for the eastern U.S. was complicated as it flanked two large high-pressure centers or heat domes over the western U.S. and western Atlantic Ocean. Being in the transition zone between these systems promoted our variable weather.

Year to date

With 2021 half over, the year ranks right in the middle of the pack in terms of temperatures over the last decade and toward the wetter side on rainfall.

How’d we do?

One month ago on June 1, Matt Ross issued Capital Weather Gang’s summer outlook. The forecast was for the June temperature to end up between normal and one degree above normal. The outcome of 0.3 degrees above normal definitely fit within that range. While a June-only precipitation forecast was not issued, the general summer idea presented of near to above normal rainfall worked out as well.