Boise, Idaho — An unseasonable surge of early-season heat will build across Idaho starting Friday, May 8, pushing temperatures well above normal and increasing risks for travel and outdoor exposure across Boise, Twin Falls, Idaho Falls, Pocatello, and Coeur d’Alene.
According to NOAA’s Climate Prediction Center, temperatures will trend 70–80% above normal through May 14, with the most intense heat arriving Friday afternoon. The peak window runs from 2 p.m. to 7 p.m. Friday and Saturday, when valleys and lower elevations are expected to heat rapidly under strong high pressure.
That heat will translate into immediate impacts. Road surfaces along I-84 and I-15 may become extremely hot during peak afternoon hours, increasing the risk of tire failures and vehicle overheating, especially across long rural stretches between Boise and Twin Falls. In urban areas like Boise, heat buildup on pavement will push surface temperatures higher than surrounding areas.
Limited overnight cooling will add to the strain. Temperatures will remain elevated after sunset, particularly in the Snake River Plain, reducing relief and increasing exposure risks for outdoor workers and those without reliable cooling.
Dry conditions combined with heat may also elevate fire risk in southern and central Idaho, especially near Twin Falls and Pocatello where vegetation can dry quickly.
This is part of a broader shift as strong high pressure expands across the western United States, driving unseasonable heat inland.
Residents should limit outdoor activity during peak afternoon hours, stay hydrated, and avoid prolonged sun exposure. Drivers should check vehicles before travel and remain alert for heat-related issues on highways.
The highest risk for heat-related impacts will occur each afternoon between 2 p.m. and 7 p.m. Friday through Sunday.
