Weathercatch: Why is October the year's most fitful month?

<p><p>This month got off to a fantastic start with a string of warm, sunny days that departed Wednesday. Where mostly clear skies ruled and temperatures ran as high as 74 degrees, now they’re in the mid-50s with increased clouds and the threat of major overnight frost.</p></p><p><p>It should come as no surprise. It’s October, after all, when weather patterns vary – and even surprise – more than any other month. As vestiges of summer give way to hints of winter, daily weather can bounce from very warm to downright chilly, dry to downpours, from mild to widespread frost and even snowy.</p></p><p><p>There’s a lot of push and pull that goes on in October, making it a tricky transitional month that’s difficult to forecast beyond four or five days. The sun, though still giving off warmth, is retreating. The jet stream, rivers of wind located high in the atmosphere, is descending southward over our region. Strong high-pressure ridges that block clouds, storms and cold fronts are losing their resilience.</p></p><p><p>All said, the atmosphere is in a heightened state of flux. In Spokane, no other month can boast a record high of 87 degrees and a record low of 7 degrees – Oct. 4, 1943 and Oct. 31, 2002, respectively.</p></p><p><p>While the day-to-day forecast can be challenging to predict beyond several days, there’s one thing we know for certain: Change is in the air. Temperatures toward the end of the month will be considerably cooler than at the beginning. On Oct. 1, the average high runs in the mid- to upper-60s. By Halloween, it hovers around 50. The average low temperature dips from 42 degrees to 34.</p></p><p><p>There’s a good chance we’ll experience more clouds rolling in and some bursts of wind and rain. We’re also likely to wake up to our first widespread hard frost.</p></p><p><p>As for snow? It’s not common, but it does happen – twice in recent years, in fact. Last year on Oct. 23, a record-breaking 6.9 inches of snow fell on Spokane, followed by another 0.6 of an inch on Oct. 24, making for an extraordinarily early major snow event. In 2019, a total of 3.6 inches fell on Oct. 8-9, a record breaker for that date.</p></p><p><p>While September is fairly steady-eddy, October is a seesaw. In a matter of days, we can go from opening windows to turning on space heaters. Sounds like this week, doesn’t it?</p></p><p><p>That said, temperatures this weekend should continue to run on the cool side, but still fairly pleasant. On Saturday, highs should run in the upper 50s with plenty of sunshine. Similar temperatures are expected on Sunday, along with a slight chance of rain. Patchy frost is possible on both mornings, which could put an end to 2021’s growing season.</p></p><p><p>———</p></p><p><p><em>Nic Loyd is a meteorologist in Washington state. Linda Weiford is a writer in Moscow, Idaho, who’s also a weather geek. Contact: ldweiford@gmail.com</em></p></p>