Heat advisories issued across western U.S., temperatures forecast up to 44.4°C (112°F) in parts of California
Multiple heat advisories were issued across portions of California, Oregon, Washington, and Nevada on June 15, 2026. Temperatures are forecast to exceed 40°C (104°F) and could reach up to 44.4°C (112°F) in Trinity County, California.
Image credit: MSEMA
Heat advisories were issued across much of California, Oregon, Washington, and Nevada on June 15, as National Weather Service (NWS) offices warned of dangerous heat, elevated overnight temperatures, and an increased risk of heat-related illness.
The most extreme temperatures are forecast in interior northern California, with forecast highs of 44.4°C (112°F). Meanwhile, unusually warm nights across parts of Oregon and Washington are expected to limit overnight cooling and increase cumulative heat stress.
Northern California
The NWS Eureka office continues Heat Advisories for Interior Del Norte, Northeastern Interior Mendocino, Southern Trinity, Northeastern Trinity, Northwestern and Central Trinity, Northern Lake, and Northeastern Interior Humboldt counties.
Forecast highs generally range from 36 to 44°C (97 to 112°F), with Moderate to Major HeatRisk expected across many interior valleys.
The highest temperatures are forecast in Northwestern and Central Trinity County, where temperatures could reach 44°C (112°F). Interior Humboldt County may see temperatures as high as 43°C (110°F), while Northern Lake County is forecast to reach 37 to 40°C (98 to 104°F).
Central California
A Heat Advisory remains in effect through 23:00 PDT Tuesday across much of the San Joaquin Valley and adjacent foothill communities.
The NWS Hanford office forecasts temperatures up to 39°C (102°F) and warns of a moderate risk of heat-related illness among older adults, infants, outdoor workers, athletes, people without effective cooling, and those with chronic medical conditions.
Southern Oregon and Northern California
Multiple advisories remain active across southern Oregon and northern California under the NWS Medford forecast area.
Western Siskiyou County is forecast to experience some of the region’s hottest conditions, with temperatures reaching 38 to 43°C (100 to 110°F).
Central and South Central Siskiyou counties are expected to see highs of 34 to 40°C (94 to 104°F), while Jackson County, Josephine County, and portions of Douglas County are forecast to reach the mid-30s to around 40°C (mid-90s to around 104°F).
Most advisories across the Medford forecast area remain in effect through Monday or Tuesday evening, depending on location.
Oregon and Southwest Washington
A broad Heat Advisory remains in effect through 23:00 PDT Tuesday for portions of Oregon and southwest Washington.
Forecast highs of 34 to 37°C (93 to 98°F) are expected across the Willamette Valley, Columbia River Gorge, Cascade foothills, Coast Range valleys, and adjacent lowlands.
The NWS Portland office said Monday is expected to be the hottest day of the event. Overnight temperatures between 15 and 18°C (60 and 65°F) will provide limited relief.
Forecasters also noted a 10–20% probability that some locations remain above 21°C (70°F) overnight, particularly across parts of the Coast Range and western Willamette Valley.
Western Washington
Heat Advisories remain active until 05:00 PDT Tuesday for Seattle, the Eastside, portions of the Puget Sound lowlands, the North Cascades foothills, and parts of the Olympic Peninsula.
Forecast highs generally range from the upper 20s to mid-30s Celsius (mid-80s to mid-90s Fahrenheit), depending on location.
The NWS Seattle office said the warmest daytime temperatures are expected Monday afternoon, while the warmest overnight lows are expected Monday night into Tuesday morning.
Localized areas of Major HeatRisk are possible in the Tacoma area, Kent–Auburn Valley, and other inland locations away from marine influence.
Central Oregon and Eastern Washington
The NWS Pendleton office has advisories in effect for Central Oregon, the Yakima Valley, Kittitas Valley, and the Columbia River Gorge.
Temperatures of 32 to 38°C (90 to 100°F) are forecast Monday, creating a moderate to major risk of heat-related illness.
The NWS Spokane office has also issued a Heat Advisory for the Moses Lake and Wenatchee areas.
Temperatures there are expected to reach 35 to 38°C (95 to 100°F), with moderate to locally major heat-related illness risk.
Nevada
The NWS Reno office has issued a Heat Advisory for the Western Nevada Basin and Range, including Pyramid Lake, from 11:00 PDT Tuesday through 05:00 PDT Wednesday.
Forecast temperatures are expected to reach 37 to 39°C (98 to 102°F), while overnight lows remain between 18 and 21°C (65 and 70°F).
Forecasters expect widespread Moderate HeatRisk with isolated areas of Major HeatRisk in lower valleys.
References:
1 Heat Advisory – NWS – June 15, 2026
I am an Assistant Editor and Severe Weather & Science Journalist at The Watchers, specializing in real-time severe weather coverage, geophysical event reporting, and research-driven scientific analysis. You can reach me at rishav(at)watchers(.)news.
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