You’ll want to stay indoors as much as possible.
The good news is that this batch is probably the main event, which means the fireworks are still on. It’s very humid, though.
Be alert for thunder and be flexible in your plans, and have indoor shelter options nearby by tonight. Also, be sure to stay hydrated and seek shade whenever possible. In addition to the potential for one or more intense storms tonight, we have reduced air quality and high heat index values around 100 degrees.
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Until tonight : The thunderstorms, some of which could become severe with high winds, dangerous lightning, and torrential rain, may not end before the fireworks on the National Mall. Timing is tight tonight, with one or more rounds of thunderstorms potentially occurring, but nearly all activities should be over by 11 p.m. Rain gear and nearby Type B shelters are recommended. More details on this severe weather threat can be found below.
The risk of heat-related illness remains high until 8 p.m. for those outdoors, with heat index values (temperatures and humidity) only slowly dropping into the mid-90s. By sunrise, the thermometer alone is expected to dip into the 60s and 70s. Expect very humid conditions in the height of summer.
Tomorrow (Friday): It could be 43.3°C in the warmest and most humid places. Some clouds are expected due to possible showers or thunderstorms early in the day. South-westerly breezes become more noticeable as the risk of showers and thunderstorms increases in the mid-afternoon or evening. The strongest thunderstorms could remain west of the city. The thermometer peaks at a few degrees near 35°C before dropping to the low 21°C range overnight.
Risk of severe storm until this evening
We could see one or more rounds of severe storms this afternoon and evening, with damaging winds gusting over 57 mph (92 km/h), frequent lightning, and torrential rain. Let’s look chronologically at the “marginal” (1 in 5) risks of severe storms tonight:
- What:Potential for multiple storm series as opposed to a definitive line or group
- Hourly:From 3pm to 7:30pm for the greatest potential for severe thunderstorms, with less intense thunderstorms still possible until late evening
- Threats:Devastating wind gusts of over 92 km/h (graph above); some torrential rain (graph below) with slow-moving thunderstorms; and frequent and dangerous lightning
- Geography:Thunderstorms will generally move from west to east, likely forming over the mountains west of our view early this afternoon. Thunderstorms will move toward and east of Washington DC in the evening.
- Comment:While our severe storm threat level is not huge and widespread, we are reporting it a little more loudly than usual because this holiday is a time when we are all much more likely to be outside and vulnerable to severe weather.
