The National Weather Service issued a heat advisory for McLean, Great Falls and all of Fairfax County in effect from 11 a.m. to 8 p.m. Wednesday, July 15, with forecast highs of 99°F and heat index values up to 105°F.
The combination of high temperatures and humidity "may cause heat illnesses," according to the NWS advisory text, which covers portions of the D.C. metro area including central, northern and northwest Virginia.
As of publication, Fairfax County had not confirmed whether it would formally activate its Heat Plan for Wednesday. The county's policy calls for activation when the forecast heat index reaches 105°F or higher, which opens libraries, community centers and other public facilities as cooling centers.
Where to cool off
Residents looking for relief have several options. A Fairfax County Public Library spokesperson confirmed that Great Falls Library and Herndon Fortnightly Library are available as cooling centers. Additional nearby options include the Reston Human Services Building, the Cathy Hudgins Community Center, the Sully Community Center and the Lake Anne Human Services office.
"Visitors seeking library services are encouraged to visit our nearby locations including Herndon Fortnightly Library and Great Falls Library," an FCPL spokesperson told FFXnow.
What to do if the power goes out
The Fairfax County Department of Emergency Management and Security published guidance on Tuesday, with one key threshold: if indoor temperatures climb above 90°F during a power outage expected to last several hours, leave for a cooler location rather than wait it out.
The NWS advisory also recommends checking on relatives and neighbors, especially older adults and those without air conditioning.
Second heat event in two weeks
This marks the second significant heat event in Fairfax County in roughly two weeks. An extreme heat warning the week of Saturday, July 4, pushed temperatures into triple digits. Wednesday's advisory forecasts a high just below 100°F.
The NWS is also forecasting highs of 99°F on Thursday, July 16. No separate advisory for Thursday had been issued as of early Wednesday.
Fairfax County's extreme heat resources are available at fairfaxcounty.gov/topics/extreme-heat-resources. Residents experiencing a heat-related medical emergency should call 911.
