The good news is that earlier rainfall has cooled temperatures to around 26 to 27 degrees Celsius in most places, although it is still very humid.
4:45 PM — Storms in the immediate area
Thunderstorms are approaching the city and the National Mall. The leading edge is around a line from Great Falls, Oakton to Fairfax and moving east.
Storms will be in the Beltway from about 5:00 to 6:00 p.m., with the first rain possibly arriving earlier. Very heavy rain and lightning are likely in the storm path.
If possible, try to stay indoors as much as possible.
The good news is that this batch is likely to be the main event, meaning fireworks can still go ahead. Very humid though.
Listen for thunderstorms and be flexible in your plans, and make sure you have shelter indoors from now until tonight. Also, stay hydrated and seek shade as much as possible. In addition to the possibility of one or more intense storms tonight, we have degraded air quality and high heat index values around 100 degrees.
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See you tonight: Thunderstorms — some of which could become severe, with damaging winds, dangerous lightning, and flooding — may not end before the fireworks on the National Mall. Timing is still being determined tonight, with one or more storms possible, but most activities should be wrapped up by 11 p.m. Rain gear and nearby Plan B shelters are advised. More information about this severe weather threat can be found below.
An increased risk of heat illness persists until 8 p.m. for those outside, with heat index values (temperatures plus humidity) only slowly dropping into the mid-90s. By sunrise alone, the thermometer should drop into the upper 60s to mid-70s. Expect very gloomy midsummer conditions.
Tomorrow Friday): It could feel like 110 degrees in the afternoon in the warmest and most humid places. There should be some clouds from possible early showers or storms. Winds from the southwest will become more noticeable as the chance for showers and storms moves in the afternoon and into the night. The strongest storms are likely to remain west of the city. The thermometer will peak within a few degrees of 95 before dropping to the steamy 70s overnight.
Chance of heavy storm tonight
We could see one or more rounds of severe storms this afternoon into tonight with devastating winds over 57 mph, frequent lightning, and flooding. Let’s look at the “marginal” (1 out of 5) overall chance for severe storms tonight chronologically:
- What: Potential for multiple rounds of storms rather than one definitive line or cluster
- Time of day: 3:00 PM to 7:30 PM for the greatest chance of severe storms, with less severe storms still possible late into the evening
- Hazards: Damaging wind gusts in excess of 57 mph (image above); a few downpours (image below) with slow-moving storms; and frequent, dangerous lightning strikes
- Geography: Storm movement will generally be from west to east, likely forming over mountains west of us early in the afternoon. Storms will move toward and east of DC in the evening.
- Commentary:Although the chance of a severe storm is not very big and widespread, we do report it a bit louder than usual. This holiday we are all outside much more often and vulnerable to extreme weather conditions.