With the autumn equinox slightly more than a week away, we’re in the midst of a delightful warm spell.
Typically, high temperatures in the Spokane area would be in the low 70s in mid-September, but not this year. As leaves take on subtle hues of orange and yellow and the amount of daylight decreases, temperatures 10 degrees higher than normal and more make it feel more like summer than fall across the Inland Northwest.
The National Oceanic and Atmospheric Administration’s Climate Prediction Center is favoring above-average temperatures to continue through Sept. 24. So while the departure from normal isn’t breaking records – so far, at least – its longevity could turn out to be noteworthy. Which isn’t to say we won’t see a cooler day here and there. For example, an unsettled weather system is expected to lower temperatures into the mid-60s on Tuesday. Overall, however, NOAA is estimating that conditions will be mostly mild and dry through the latter part of the month.
The span of analogous warmth began in earnest last weekend when Spokane International Airport reached a high of 83 degrees Saturday and 86 degrees Sunday. Meanwhile, the thermometer reached 92 degrees in Lewiston on Saturday, followed by 95 the next day, and 87 degrees in Omak, Washington, followed by 91 Sunday. Even the region’s overnight lows ran above normal, but to a lesser degree than daytime highs.
The spike in temperatures was caused by a high-pressure system centered along the Continental Divide. It drifted east on Monday, resulting in slightly cooler weather, some cloudiness and a few sprinkles in some locations. Even so, temperatures ran slightly above normal for this time of year.
Another high-pressure system that began building on Wednesday is expected to bring a steady temperature climb that returns the Inland Northwest to 80- to 90-degree weather through the weekend. If this were late June, the same pattern would have us fanning ourselves against extreme heat.
Instead, thanks to decreasing daylight hours and weakening intensity of the sun, we’re welcoming the remnants of summer before true autumn hints of winter.
Nic Loyd is a meteorologist in Washington state. Linda Weiford is a writer in Moscow, Idaho, who’s also a weather geek.