A July heat wave across the Inland Northwest is going to strengthen today through Thursday, keeping temperatures in the 90s and perhaps triple digits.
A weak upper-level low pressure area that brought thunderstorms to the region Monday is moving to the east, allowing a persistent high pressure system to rebuild along the West Coast.
Monday’s high hit 95 at Spokane International Airport before a thunderstorm cooled the temperature back to the 70s after 5 p.m.
The National Weather Service is warning people to be wary of the heat and avoid strenuous activity in the afternoon.
The forecasted highs for the Spokane airport are 95 today, 98 on Wednesday and 95 on Thursday.
Locations within the city may see highs a few degrees warmer due to pavement and buildings that absorb heat.
A high of 100 degrees is expected Wednesday in downtown Spokane.
Coeur d’Alene will have highs of 90 today, 95 on Wednesday and 91 on Thursday.
The heat wave prompted Spokane city leaders to extend pool hours starting on Friday through Sunday. Comstock, Hillyard, Cannon, Liberty and Shadle pools will be open from 1 to 6 p.m. on each of those days.
Spokane County pools will offer free swimming from 10:30 a.m. to 5:30 p.m. this Saturday.
July has been one hot month so far.
Through Sunday, the daily average temperature has been 8.7 degrees above normal this month. Also through Monday, July has logged 10 days at 90 or above.
The weather service issued a heat advisory on Monday for the Columbia Basin, Central Washington, the Palouse, Lewiston and Walla Walla regions, with highs going from 100 to 108 degrees and lows staying above 65 degrees at night.
“With light winds expected Tuesday, the afternoon heat will be particularly brutal at elevations below 1,500 feet along the Columbia, Okanogan, Snake and Clearwater rivers,” forecaster Greg Koch said in Monday afternoon’s forecast discussion on the weather service website.
Spokane is in the middle of a streak of nine days with highs of 90 or warmer. The record streak is 13 days in August 1981, forecasters said. However, the forecast for the airport has the temperature dropping to 88 on Friday, which would tie the record.
On Thursday, a weak cold front is expected to pass over the region and trigger a slow cooling trend. Another weak low should pass through British Columbia over the weekend to help moderate temperatures back to the 80s.
However, the Thursday cold front will also create windy conditions in the fire-prone areas on the east slopes of the Cascades in Yakima and Kittitas counties. A fire weather watch was posted for those regions.
Temperatures are expected to cool to the middle 80s on Saturday through Monday.