When will it rain? This weekend’s weather outlook amid ongoing wildfires

Many are now asking—when will it really rain? There are concerns about the ongoing wildfires across the Pacific Northwest, wildfire smoke and poorer air quality, and simply—it is just too dry! Rain is needed to douse the fires, cleanse the air, and have nature irrigate the landscape.

The lingering pleasant summer weather is also welcomed by many with this week’s morning clouds and fog, and afternoon sunshine with high temperatures climbing into the 70s. Yet, some are singing the Creedence Clearwater Revival song—”Have You Ever Seen The Rain?”

Seattle weather forecast—rain this weekend?

Heading into the weekend, some rain is set to arrive. If you have weekend plans, Saturday is the day for outdoor activities. Higher pressure aloft is forecast to hold, resulting in another day of morning clouds and fog, revealing afternoon sunshine and high temperatures again reaching the 70s. If heading to the mountains, freezing levels will be way up there, around 14,000 feet.

By Sunday, though, the high pressure aloft is expected to shift inland as a weakening Pacific weather system works its way onshore, bringing showers to much of western Washington and cooler temperatures. Highs are forecast to drop into the 60s. Coastal areas and the mountains may receive 1/2 to 1 inch of rainfall, while the western interior is anticipated to get perhaps as much as a quarter inch or more. Mountain snow levels are forecast to drop to near 8,000 feet.

Looking at next week’s forecast

But that’s it for a while as higher pressure is forecast to rebuild over the Pacific Northwest next week for a return to dry weather and more afternoon sunshine following morning clouds and fog.

Any lingering showers will taper off by Monday morning, and before mid-week, high temperatures are expected to climb back into the 70s across much of the western Washington interior.

Oh so dry

The region could sure use the rain. According to the U.S. Drought Monitor, much of the state is in moderate to extreme drought. The year’s rainfall statistics back that up.

For instance, the Seattle-Tacoma International Airport (SEA) is over 2 2/3 inches behind on rainfall thus far this year—only 70% of average. Olympia has a nearly 10-inch rain deficit for the year, 65% of normal. Usually wet Forks on the north coast is close to a giant 24 inches of rain behind for the year, only 59% of average.

The latest weather outlook that runs into the fourth week of this month shows good chances of above-average temperatures and near or below normal precipitation. The average high temperature in mid-September is in the mid-70s. By the time the calendar reaches the fall equinox on September 22, average high temperatures edge down to around 70 degrees thanks to shorter days and longer nights.

This time of year, the region is losing close to 3 1/2 minutes of daylight each day. The last 7:30 p.m. sunset of the year in Seattle was on September 10. September 25 will mark the final 7 p.m. sunset of the year.

Any significant rain in sight?

In the longer range, is there any significant rain in sight? If extended forecast guidance is any indication, nothing substantial is anticipated. It may take until near the end of this month or into early October before a real ‘wetting rain’ could unfold.

Reviewing the latest seasonal outlook for this fall and winter, the trend is for a weak La Niña to return for this winter.

La Niña is the opposite sibling of El Niño, when the ocean waters in the eastern Pacific Ocean tropical waters—the waters west of Peru—are cooler than average. El Niño is when those same tropical waters are warmer than average.

La Niña and El Niño make big adjustments in how the North Pacific storm track behaves. For La Niña, Pacific storms spend more time moving onshore into the Pacific Northwest as opposed to El Niño, when the storm track takes a more constant path into California and beyond across the southern tier of the U.S.

El Niño winter seasons for western Washington tend to be warmer than average and lean toward below-average precipitation and a much poorer mountain snowpack.

La Niña winters are sharply different. They tend to be cooler and wetter than average, and produce a healthy mountain snowpack. The current seasonal weather outlook reflects that pattern, and if it pans out, then more rainfall and mountain snow lie ahead this winter. By then, perhaps some will be singing Supertramp’s “It’s Raining Again.”

Ted Buehner is the KIRO Newsradio meteorologist. Follow him on X and Bluesky. Read more of his stories here.