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ALEXANDRIA, Va. — Alexandria's dangerous heat stretch is over. The National Weather Service issued no heat advisories or warnings Monday for the first time since Wednesday, July 1, ending a six-day run in which the region operated under an active heat alert every single day — including three days under an Extreme Heat Warning with observed heat index values that reached 112 degrees.
Monday itself is transitional. The forecast high is 90 degrees, with a heat index up to 101 — hot, but no longer at the level requiring an NWS advisory. And no day for the rest of the week reaches those thresholds either. Tuesday's high is forecast at 84, Wednesday at 84, Thursday at 89, Friday at 93, Saturday at 89, and Sunday at 87. The seven-day forecast doesn't include a single high above 93 or a heat-index note.
But the weather isn't done demanding attention.
A flash flood risk this afternoon
The National Weather Service has issued a Flood Watch covering Alexandria and the broader I-95 corridor from 4 p.m. Monday through midnight, warning that flash flooding caused by excessive rainfall is possible. The NWS notes that "multiple rounds of heavy rainfall are possible this afternoon and evening, some of which may occur over areas which recently experienced flooding rains." Slow storm motions and repeat thunderstorm activity within a tropical air mass could push hourly rainfall rates into the 2- to 3-inch range in the strongest storms, with higher instantaneous rates possible.
A few severe thunderstorms with damaging wind gusts are also possible this afternoon and evening. Storm activity begins as early as this morning, with showers and thunderstorms likely before 4 p.m. and continuing into the evening. The rainfall totals through tonight could reach up to three-quarters of an inch, with substantially higher amounts possible under any individual thunderstorm cell.
The Hazardous Weather Outlook warns that "spotter activation may be needed today for the flash flood threat" — meaning NWS trained spotters may be called on to help track storm impacts.
What the last week actually delivered
The heat stretch that ended Sunday night began Wednesday, July 1 with a Heat Advisory, escalated to an Extreme Heat Watch Thursday, became an Extreme Heat Warning Thursday afternoon through Saturday evening, and returned to Heat Advisory territory Sunday. The forecast peaks were routinely dangerous; the observations at Reagan National Airport confirmed them.
Friday, July 3 delivered the stretch's peak. The temperature reached 102 degrees at Reagan National at both 3:52 p.m. and 4:52 p.m., with a heat index that touched 112 degrees during those same hours. Humidity dropped to 38% at midday — arid by Alexandria standards, driven by the extreme heat — even as the heat index climbed. Overnight lows barely provided relief; the temperature never fell below 87 degrees at DCA during Friday's overnight period.
Saturday's Fourth of July repeated the pattern in a compressed window. The observed temperature reached 102 degrees at 5:52 p.m., with a heat index of 107. Then the storms arrived.
A severe thunderstorm swept through the region between 6 and 7 p.m., dropping the temperature at Reagan National from 102 degrees at 5:52 p.m. to 88 degrees at 6:52 p.m. — a 14-degree fall in an hour. The storm brought southwest wind gusts up to 37 mph, moderate rain, and the first meaningful precipitation of the stretch. It was the kind of outflow-driven event forecasters had warned of, and it arrived on the day forecast to produce it.
Sunday morning brought a different weather signature: dense fog, with visibility falling to three-quarters of a mile at 3:52 a.m. and remaining below four miles until nearly 9 a.m. The fog was the atmospheric consequence of overnight cooling meeting the extreme humidity left by Saturday's storms — a small but striking detail from a week defined by extremes.
Sunday afternoon's heat index still reached 107 degrees at 4:52 p.m., under the Heat Advisory that ran until 8 p.m. It was the last dangerous heat reading of the stretch.
Cooling resources close
The DASH cooling bus at 417 King Street closes today at 4 p.m., matching the deployment window announced Wednesday. The second DASH bus at the LA Mart parking lot completed its Friday-only deployment. Charles Houston and Patrick Henry recreation centers return to their normal weekday operating schedules.
Carpenter's Shelter at 2355 A Mill Road, which had extended overnight hours through 7 a.m. Monday for those in need of overnight shelter during the heat stretch, resumes its normal schedule.
Rain will continue through the week
The pattern that ended the heat wave brings its own rhythm. Tuesday, Wednesday morning, Thursday afternoon, Friday afternoon, and Saturday all include a chance of showers and thunderstorms in the forecast. Cumulative rainfall could contribute to what the NWS calls "urban or poor drainage flooding" — meaning storm drains overwhelmed, low-lying areas pooled, and creeks temporarily running high.
Alexandria is particularly susceptible to this kind of localized flooding, with waterways including Cameron Run, Hooffs Run, and Four Mile Run all handling storm runoff for large portions of the city. Any of them can rise quickly during heavy rain, and multiple neighborhoods have experienced flash flooding events in recent years that prompted the city's ongoing stormwater infrastructure investments.
Safety guidance for the flood risk
The Alexandria Emergency Management Office reminds residents that flash floods can develop quickly and that vehicles should never be driven through flooded roadways — as little as six inches of moving water can knock down an adult, and as little as two feet can carry away most vehicles. The phrase "turn around, don't drown" applies to any road covered by unknown depth of water.
Residents with basement drains, sump pumps, or other flood-prone conditions should check now that equipment is functional and clear of debris. Anyone with outdoor plans this afternoon and evening should watch weather radar and be prepared to move indoors quickly.
For non-emergency questions about flooding or city services, call Alex311 at 703-746-4311 or visit the Alex311 portal. For emergencies, including road flooding that requires response, call or text 911. Updated status information is available at the city's Current Alert Status page.
The next Heat Advisory or Extreme Heat Warning threshold in Alexandria won't be reached again this week — a genuine break, if not a completely quiet one.
