National Weather Service issues heat advisory for northwest Washington, including Whatcom County

WHATCOM COUNTY, Wash. — According to the US National Weather Service (NWS) Seattle office, a heat advisory will be effect from about 10am on Tuesday, July 21, 2026, to about 11pm on Wednesday, July 22, 2026.

The advisory includes the lowlands of western Whatcom County, the eastern Strait of Juan de Fuca, the foothills and valleys of the North Cascades, the Lake Crescent area including US 101, the lowlands of western Skagit and northwestern Snohomish counties, the northern Hood Canal, and the Port Townsend area.

High temperatures up to 85 to 90 degrees and low temperatures from 58 to 62 degrees are expected, according to the NWS. These conditions present a moderate risk of heat-related illness for individuals sensitive to heat, particularly those without effective cooling or adequate hydration. Areas closest to the water will experience cooler daytime high temperatures.

According to the Occupational Safety and Health Administration, scheduling frequent rest breaks in shaded or air-conditioned environments is recommended to reduce risk during outdoor work. The NWS statement notes that anyone overcome by heat should be moved to a cool and shaded location, and heat stroke is an emergency that requires calling 911.

The following are high temperatures forecast across Whatcom County according to the meteoblue forecast as of 11am on Sunday, July 19, 2026.

Whatcom News readers are encouraged to stay up to date with current weather alerts and forecasts and air quality readings for their specific Whatcom County locations along with tide tables via the Whatcom News Weather page.