(Updated at 10:45 a.m.) Arlington County and surrounding areas are under a Heat Advisory for much of Wednesday.

Forecasters say the heat index could hit 105 degrees, signalling dangerous conditions for anyone spending time outdoors.

The Heat Advisory will take effect at 11 a.m. and is scheduled to end at 8 p.m. More from the National Weather Service:

…HEAT ADVISORY IN EFFECT FROM 11 AM TO 8 PM EDT WEDNESDAY… THE NATIONAL WEATHER SERVICE IN BALTIMORE MD/WASHINGTON HAS ISSUED A HEAT ADVISORY, WHICH IS IN EFFECT FROM 11 AM TO 8 PM EDT WEDNESDAY. * HEAT INDEX VALUES…AROUND 105 DEGREES WITH TEMPERATURES IN THE MIDDLE 90S AND DEWPOINTS IN THE LOWER TO MIDDLE 70S. * IMPACTS…THE HEAT AND HUMIDITY MAY CAUSE HEAT STRESS DURING OUTDOOR EXERTION OR EXTENDED EXPOSURE. PRECAUTIONARY/PREPAREDNESS ACTIONS… A HEAT ADVISORY MEANS THAT A PERIOD OF HIGH TEMPERATURES IS EXPECTED. THE COMBINATION OF HIGH TEMPERATURES AND HIGH HUMIDITY WILL CREATE A SITUATION IN WHICH HEAT ILLNESSES ARE POSSIBLE. TAKE EXTRA PRECAUTIONS IF YOU WORK OR SPEND TIME OUTSIDE. WHEN POSSIBLE, RESCHEDULE STRENUOUS ACTIVITIES TO EARLY MORNING OR EVENING. KNOW THE SIGNS AND SYMPTOMS OF HEAT EXHAUSTION AND HEAT STROKE. WEAR LIGHT WEIGHT AND LOOSE FITTING CLOTHING WHEN POSSIBLE AND DRINK PLENTY OF WATER. TO REDUCE RISK DURING OUTDOOR WORK, THE OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION RECOMMENDS SCHEDULING FREQUENT REST BREAKS IN SHADED OR AIR CONDITIONED ENVIRONMENTS. ANYONE OVERCOME BY HEAT SHOULD BE MOVED TO A COOL AND SHADED LOCATION. HEAT STROKE IS AN EMERGENCY – CALL 911. &&

A Heat Advisory has been issued for counties along/east of the I-95 corridor, including DC and Baltimore. Heat index values are expected to reach 105 degrees for areas in the advisory. #DCwx #MDwx #VAwx #WVwx pic.twitter.com/unclowshfB

— NWS DC/Baltimore (@NWS_BaltWash) July 17, 2019

Arlington County will be opening overflow space in its Homeless Services Center in Courthouse through Sunday night due to the dangerous heat. Authorities are also encouraging residents to drink lots of fluids and limit time outdoors, especially for the elderly and pets.

Significant heat will remain in the area over the next several days. Remain hydrated, limit your time outdoors, wear lightweight clothing and check on the elderly and pets. Additional tips available at https://t.co/dlWskFxFpq. #ArlWX https://t.co/4LGZyWOgb5

— ArlingtonCountyPD (@ArlingtonVaPD) July 17, 2019

When you get where you’re going, #lookBeforeYouLock. Make sure children & pets are out of the vehicle. If you come across an idle vehicle with a child or pet inside, call 9-1-1 immediately. #BeatTheHeat #HeatSafety pic.twitter.com/3iiA0fYEQp

— Arlington Fire (@ArlingtonVaFD) July 17, 2019

Flickr pool photo by Erinn Shirley