Wednesday may have been the last day you will need air conditioning this summer in Western Washington.

And fears of wildfires west of the Cascade crest should fade as well, according to University of Washington meteorologist Cliff Mass.

“Heavy rain is coming to Western Washington, accompanied by dramatically cooler temperatures,” he said. “When I plotted the predicted accumulated rainfall through Saturday morning from the UW model forecast, I could hardly believe my eyes. Was it mid-August or September?”

Expect 2-5 inches of rain on the western slopes of the mountains, enough to radically reduce subsequent wildfire threats for much of the region.

Importantly, lots of rain will push into Eastern Washington. Several Western Washington rivers will surge to near record levels (for this time of the year). For example, the flow of the Snoqualmie River will jump dramatically.

The level of the Skohomish River, not far from the Bear Gulch Fire on the Olympic Peninsula, will surge upwards as well due to the heavy rain on the Olympics.

“If this is not shocking enough, check out the predicted temperatures from the NOAA/NWS GFS model for Seattle,” Mass said. “Low 90s today (Wednesday), Low 70s tomorrow (Thursday),” he said. “But the shocker is Friday. Highs in the low 60s. Stunning.”

Meteorologist Scott Sistek echoes Mass’ prediction.

“Unlike last week whose rain was more like ‘that’s nice,’ this rainy pattern is more like it just fell out of a time portal from November,” Sistek said. “Or to keep with the movie theme from my last post on my timeline here, this is ‘Freakier Friday’ — only this time it’s summer and autumn who have swapped bodies.

“A robust low pressure center has tapped into a powerful plume of moisture that, I can’t believe I’m saying this in August, has all the markings of a decent atmospheric river. In fact, the folks at San Diego State who monitor and rate atmospheric rivers are giving this storm a level 3 (out of 5) on their scale. Again, routine in November, very rare in August.”

The bulk of the rain comes Friday night into early Saturday morning, then lingering showers through the weekend.

— The Seattle Times and The Olympian contributed to this report.