Heat advisory issued for D.C. on Saturday, when it could feel like 105-plus

The Weather Service is warning that “oppressive heat and humidity will overspread the area Saturday and last into Sunday” and to expect “dangerously hot conditions” in which “heat related illnesses increase significantly.”

The heat was already ramping up on Friday, with high temperatures expected in the mid-90s and heat indexes, which also factor in humidity, near 100 degrees.

Air temperatures near the century mark are predicted for both Saturday and Sunday, with heat indexes 5 to 10 degrees higher. Standing in the way of any hope for significant relief, temperatures at night won’t fall below the mid-70s to near 80.

If it does hit 100 in the city, it will be the first time since August 2016. The District is in the midst of the fifth-longest streak on record without reaching 100.

Even if it doesn’t reach 100 this weekend, the ongoing heat wave marks one of the longest in several years and is happening unusually early in the summer.

The Weather Service’s HeatRisk outlook, on a scale from 0 to 4, is set to escalate from Level 2 on Friday to Level 4 by Sunday. The HeatRisk scale takes into account how unusual and long-lasting the heat is, as well as the anticipated threats to human health.

“Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors,” the Weather Service advises. “Do not leave young children and pets in unattended vehicles. Car interiors will reach lethal temperatures in a matter of minutes.”

Friday should end up the hottest day of the year so far with highs in the low to mid-90s. It will be the fifth straight day at or above 90 and the eighth this year.

Temperatures are likely to climb even further Saturday. The District is currently forecast to reach 100, although it’s possible it could fall just short. Most of the rest of the region is expected to reach the upper 90s, with slightly cooler air near the Potomac River and Chesapeake Bay. Afternoon heat indexes should reach at least 105.

Sunday and Saturday keep flip-flopping on which will be hottest. Like Saturday, Sunday is expected to bring highs in the upper 90s to near 100 and heat indexes of at least 105.

With predicted highs no higher than the mid-90s on Friday, most spots should fall just short of records.

Better odds for records arrive Saturday, but existing marks are all near or above 100, so many spots could fall just short again. The forecast at Dulles is 99, compared to a record of 99. In the District, the 99 in the forecast compares to 101 for a record.

Sunday seems to have the best shot to set multiple records across the local area. Washington, Dulles and Baltimore are all forecast to top records, with highs in the upper 90s or around the century mark.

Among at least 100 daily records for warm lows at risk Sunday in the eastern United States, D.C. is currently forecast to dip only to 81, which would beat the previous calendar-day record by three degrees and mark the warmest low temperature so early in the year on record.

More heat to come after the weekend

Although temperatures are forecast to head downward somewhat to start next week, they will likely remain in the low 90s before rising toward the high 90s on Wednesday ahead of a cold front.

There is increasing potential for the cold front to break the ongoing streak of 90-degree days by Thursday.

The forecast for July, just out from the Weather Service, calls for more abnormally hot weather in the Mid-Atlantic.