Monday was a scorcher in the Seattle area, with a new record set at SeaTac - 96 degrees. The old record was 95.
KING 5 Chief Meteorologist Jeff Renner said many locations hit or exceeded 100 degrees in some of the inland locations, including Carnation, Redmond, Sammamish, Kent and Auburn.
Expect increasing clouds Monday night, with a chance of showers and thunderstorms to last through Tuesday evening.
A red flag warning is in effect for most of Western Washington (with the exception of the central and north coast) until 5pm Tuesday, and over all of the Cascades and eastern Washington until 11pm Tuesday.
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A red flag warning means that critical fire weather conditions are either occurring or will shortly. A combination of strong winds, low relative humidity and warm temperatures can contribute to extreme fire behavior.
Renner said a developing low in the upper atmosphere just off the southern Oregon and northern California coast will rotate moisture into Washington later Monday and Tuesday - along with a little cooler air.
This will begin to cool our daytime highs down but it will also bring unstable air and a chance of thunderstorms. These will be accompanied by numerous lightning strikes and may trigger new wild fires, he said.
The storms may bring significant rainfall to some areas.
Flash flooding is possible in recent burn areas of the Okanogan Valley and Wenatchee areas.
By Wednesday night, the chance of showers should diminish and we'll see a return to morning clouds and afternoon sun and highs near 80 for the weekend.