The month may be mostly recalled for the continuation of a humid, wet weather pattern that began the second week of May. It resulted in rainfall on one-third of June days and pushed the month’s total to 5.21 inches, a healthy 1.43 inches above normal.
Early in the month, excessive rainfall in Washington and especially out toward the mountains pushed Potomac River levels to their 17th-highest crest in Georgetown on June 5.
June weather extremes and records
The month’s coolest weather occurred early and produced lows in the crisp 50s. It seems like a lifetime ago given the current heat wave.
The month’s hottest reading of 95 occurred June 19.
Our wettest day was early in the month before the pattern started to dry out some.
Here are the numbers for weather extremes during June 2018 at Reagan National Airport:
The heat records set during the month coincided with the heat wave around June 18 and 19:
- June 19: Record warm low temperature of 77 exceeded 75 from 2011, 1994, 1981 and 1978.
Dulles International Airport:
- June 18: Record high temperature of 94 ties 2007.
- June 19: Record warm low temperature of 71 ties 2014.
June weather pattern
After the United States endured a cool-dominated March and April, both May and June offered the opposite with widespread warmth.
Nationally, all this heat spurred the second-hottest June on record. Below is the map of temperatures differences from average during June and you can see that Washington, while warm, was spared the hottest heat:
The widespread warm conditions, which resulted from persistent hot high-pressure systems, is a summer impact from lingering atmospheric La Niña conditions. They should fade later this summer, perhaps as quickly as the second half of July.
June forecast evaluation
A month ago, just ahead of June’s start, we made the following predictions:
Temperature: 74 to 76 degrees, which is right around the normal of 75 degrees. This is similar to 2016 and cooler than last year.Rain: 3.5 to 5 inches, compared with the normal of 3.78 inches, which would make it the wettest since 2015.
Here is what actually happened:
Temperature: 76.2. This is just about in range and similar to 2016 as predicted.Rain: 5.21 inches. This is just outside the predicted range but is correctly the wettest June since 2015
Since the main themes of temperatures similar to 2016 and wettest since 2015 worked out well, we give ourselves a grade of B.
January-through-June temperature and precipitation rankings
Can you believe 2018 is half over already? Well, here is how the first half of 2018 is ranking in terms of precipitation and temperature:
It has been warmer and wetter than normal but nothing crazy or extreme.
Jason Samenow contributed to this report.