Seattle may feel mellow at around 63°F midday Monday, July 20, but that calm is not going to last. A midweek warmup is on the way that will push inland neighborhoods into the upper 80s and low 90s. The National Weather Service has a Heat Advisory in place for much of the city from 10 a.m. Tuesday, July 21, through 11 p.m. Wednesday, July 22. Waterfront spots should stay a bit cooler, but central, eastern, and foothill neighborhoods are in line for the hottest conditions and the least overnight relief.
What To Expect Tuesday Through Wednesday
Temperatures climb quickly, with NWS Seattle calling for highs near 88°F on Tuesday and around 90°F on Wednesday for inland areas. Overnight lows are expected to hang in the mid 50s to mid 60s. That one-two punch of hot days and warm nights raises the risk of heat-related illness, especially for older adults, infants, and anyone without air conditioning. The Heat Advisory highlights a "moderate to major" risk in the hottest neighborhoods and urges people to limit strenuous outdoor activity during peak afternoon hours and seek cool, air-conditioned spaces whenever possible.
Impacts And Safety
Basic rules still matter: drink plenty of fluids, avoid long stretches in direct sun, and never leave children or pets in parked vehicles, not even for a quick errand. Employers and outdoor crews should build in frequent rest breaks and shaded downtime. King County and local partners have activated Tier 2 severe-weather protocols and posted daytime cooling locations and open daytime shelters to help people ride out the heat. If you need a place to cool off, call the Severe Weather Shelter Navigation Hotline at (206) 245-1026 or check the county's activation page for the latest locations and hours. See King County for details.
Smoke And Commute Notes
A light northerly flow may drag some elevated wildfire smoke into parts of northwest Washington over the next few days. Most of that haze is expected to stay aloft, although valleys and areas near the Cascade crest could see worse conditions. People who are sensitive to air quality should be ready to head indoors if smoke cuts visibility or triggers breathing issues. On the ground, hot road surfaces and extra glare could slow morning commutes, so shifting outdoor errands and exercise to early morning or evening will be the more comfortable move.
When It Cools Down
Relief should start to show up late Wednesday into Thursday as an offshore system nudges into the region, bringing a slight chance of showers and a stronger onshore push. That pattern change is expected to cool things down, with forecasts trending back toward more typical summer highs in the 70s by Friday and into the weekend. We will post updates if the advisory timing or intensity changes.
