3-day string of 100-degree highs could include DC region’s hottest July Fourth on record

This Fourth of July is expected to be the D.C. area’s hottest on record, and the third in a stretch of brutally hot and potentially dangerous 100-degree days.

7News First Alert Meteorologist Eileen Whelan said the D.C. region will experience the hottest stretch of weather so far this year starting on Thursday and continuing through Saturday, with highs聽reaching around 100 degrees.

鈥淲e likely will have some new record highs at area airports, but with the high humidity, feels like temperatures will be at about 110 to 112 both today and tomorrow afternoons.鈥� Whelan said.

The National 蜜桃视频app Service has in effect for both Thursday and Friday.

Sunshine will dominate Thursday’s weather with little chance for cooling thunderstorms. Portions of the D.C. region have opened cooling centers in preparation for the heat wave. The region will only see slight relief from the heat and humidity in the evening, with lows slightly dipping below 80 degrees and feels-like temperatures staying around 90 until after midnight.

Whelan said Friday could bring pop-up showers and storms, and more widely scattered showers and storms are expected for the Fourth of July.

鈥淲e now are under severe risk categories from the Storm Prediction Center, both tomorrow and Saturday. A higher risk Saturday, damaging wind gusts, downpours and frequent thunder and lightning could impact your Fourth of July plans,鈥� Whelan said.

If storms move in earlier in the day on the Fourth, it might not be quite as hot, but it will still be very humid for the fireworks shows, and with light winds, the region could see a lot of smoke creating some poor air quality Saturday night.

Sunday will be slightly, slightly, cooler with highs in the 90s, but: Showers and storms are likely. A cold front will drop highs into the 80s next week, though it will still bring very extreme heat and humidity, and with the storm chances coming the next few days, they could be on the strong side.

“So just take it easy,” Whelan said.

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Metro is also watching the heat

Metro in past years has conducted “heat rides” to monitor outdoor rail temperatures and check for warping and other heat-related issues. It has also lowered train speeds when outdoor rail temperatures top 135 degrees.

“This year, we鈥檙e adding something new: applying reflective white paint to vulnerable segments, which lowers temps,” Metro said Wednesday in a post on X.

More than 6,000 feet of track were treated with the paint, the transit agency said.

With extreme heat like we鈥檙e currently experiencing, rail temperatures can soar above 135掳F, which may cause bends in the rail due to thermal expansion.

For years, Metro has monitored rail temps on 鈥渉eat rides鈥� to detect track issues before they happen.

This year, we鈥檙e鈥�

鈥� Metro Forward (@wmata)

Extreme heat presents challenges for every transit system, because our steel rails expand as temperatures increase, and the demands on our electrical and mechanical equipment increase exponentially,” Theresa Impastato, Metro’s chief infrastructure officer said.

In the system’s underground stations, chillers and fans keep temperatures about six to 10 degrees cooler than聽outside, she said.

“We monitor in real time conditions across the system and the performance of the chillers, and are prepared to respond quickly to any equipment issues that could affect our customer comfort,” Impastato said.

7News First Alert Forecast

THURSDAY:
EXTREME HEAT WARNING
Sunny, dangerous heat
Highs: 100-105
Heat Index: 108-112
Winds: Southwest 5-10 mph

THURSDAY NIGHT:
Mainly clear
Lows: 77-83
Winds: Light & Variable

FRIDAY:
EXTREME HEAT WARNING
Mostly sunny, dangerous heat
Isolated PM Storms Possible
Highs: 100-106
Winds: West 5-10 mph
The dangerous heat shows no signs of letting up. An extreme heat warning remains in effect from 10 a.m. to 8 p.m. with afternoon temperatures once again soaring between 100 and 105. Combined with tropical humidity, heat index values will climb as high as 112, making this another day of dangerous, potentially life-threatening conditions. Reagan National will once again challenge its daily record high of 101, while Dulles could approach or break its daily record of 103. By late afternoon and evening, the atmosphere becomes increasingly unstable, allowing isolated thunderstorms to develop. Any storm that forms could quickly become severe with damaging wind gusts, torrential rainfall, hail and dangerous cloud-to-ground lightning.

SATURDAY:
EXTREME HEAT WATCH TO BE ISSUED
Thunderstorm risk
Highs: around 100
Winds: West 5-10 mph
The Fourth of July remains dangerously hot with afternoon highs near or just above 100 and heat index values around 105. An extreme heat watch will be added by the National 蜜桃视频app Service within the next 24 hours. Scattered afternoon and evening thunderstorms become more likely as the weather pattern slowly weakens. Any storm that develops could produce damaging winds, torrential rain and dangerous cloud-to-ground lightning. Reagan National will once again be near its daily record high of 100, while Dulles could challenge its daily record of 97.

FIREWORKS FORECAST:
Lingering showers and storms end
Temperatures: 90s to 80s
Winds: West 2-5 mph
Most fireworks displays should be able to proceed, but conditions will need to be monitored closely. Any thunderstorms that develop during the afternoon or evening could linger into the early nighttime hours, especially east of the Blue Ridge. Outside of storms, temperatures remain in the upper 80s to lower 90s early in the evening with very high humidity. Winds will be light, generally from the west around 2 to 5 mph, so smoke from fireworks may linger longer than usual and reduce visibility at some displays. Keep an eye on radar before heading out, as any thunderstorm could quickly produce dangerous lightning and strong wind gusts.

SUNDAY:
Scattered showers, storms
Highs: 95-100
Winds: West 10-15 mph
The heat wave continues, although temperatures may ease back slightly into the middle and upper 90s. Even so, humidity remains high and heat index values will still exceed 100 degrees during the afternoon. Scattered showers and thunderstorms remain possible, with some storms capable of producing gusty winds and heavy rainfall. While there are signs this historic stretch of heat may begin to weaken early next week, Sunday will likely be another day where heat safety remains a top concern.

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蜜桃视频app’s Nick Iannelli contributed to this report.

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