Freezing temperatures expected in Coeur d'Alene in October

I know it’s sounding like a broken record, but the extremes just keep on coming. An unprecedented third Category 4 hurricane hit the U.S. Mainland and territory, Puerto Rico, for the 2017 season. As many of you know, the island was completely devastated by the massive storm, Maria, which left the entire region without power. And, the hurricane and tropical storm season doesn’t end until Nov. 30.

On the last full day of summer, Sept. 21, snow was reported in the Sierra Nevada mountains in California. The unexpected snowfall led to a 16-car pile-up that resulted in one death.

Here in North Idaho, it felt like we went directly from summer to winter. On Sept. 12, Cliff recorded a high of 89 degrees, a little short of the record of 93 degrees set back in 1948. Then, on Sept. 18, temperatures dropped and Coeur d’Alene picked up 0.53 inches of much-needed rainfall. The moisture on that date was more than the last three months combined. About an inch of snow was reported in the northern mountains early last week.

It’s almost hard to believe that we’re now talking about freezing temperatures. Earlier this month, readings dropped into the upper 20s in the outlying areas around Athol, Twin Lakes and Rathdrum.

Cliff and I don’t expect to see a hard freeze in Coeur d’Alene until around the early-to-mid portion of October. However, lows below the 32-degree mark may be reported once again in some of the outlying areas early next month.

We’re getting a lot of questions about freezing temperatures. I wanted to thank Cliff for spending several hours putting together this information.

Based on his records dating back to 1895, the lowest temperature in September was 17 degrees. That occurred on Sept. 24, 1926. The following morning, Sept. 25, 1926, the low was 22 degrees. Also, that chilly period was the only time when measurable snow was reported as an inch fell on Sept. 23, 1926.

Since 2000, the only September freeze in Coeur d’Alene happened on Sept. 24, 2005. The morning low on that date was 32 degrees.

Since 1895, the average date for the first freeze in Coeur d’Alene is Oct. 16. The coldest reading ever recorded for October occurred on Oct. 31, 1935, with a low of 8 degrees. More recently, the chilliest temperature was 19 degrees on Oct. 9, 2009. It was 20 degrees on Oct. 10, 2009. Two days later, in the same year on Oct. 12, the mercury dipped to a frigid 15 degrees. That was the worst early October coldwave to hit the region in history.

In the south-central Pacific Ocean, ocean waters are cooling down once again. It’s very possible that the cooler, La Nina, sea-surface temperature event will be declared very soon. During La Nina years, the chances for above normal snowfalls in our region go up. Therefore, we think snow totals for the 2017-18 season will be a little above the 69.8 inch normal.

Speaking of snow, there have been instances of measurable amounts of the white stuff in October in Coeur d’Alene. The most that fell was back in 1957 with 6.8 inches. Cliff’s records for Coeur d’Alene say 3 inches fell on Oct. 22 and 3.8 inches was reported on the 23rd. There was one Halloween day when 3 inches of snow fell. That occurred back in 1971. The odds of measurable snowfall this Halloween in the lower elevations are very small, but in this wild pattern of extremes, anything is possible.

In terms of our near-term weather, the rest of the month looks dry with very pleasant temperatures. If we don’t see another drop of rain in September, our total will end up at 1.44 inches. The normal rainfall for September is 1.55, so we’ll likely have another month with below-normal precipitation. But, we’re much closer to normal and the recent moisture has certainly helped the wildfire situation.

Despite the recent rainfall and cooler temperatures, there are still 38 large fires across the West. Montana is down to nine and Oregon now has 13 major blazes. Both Washington and Idaho have four big wildfires as of late last week. Since Jan. 1, more than 8.5 million acres have “gone up in smoke” in the U.S. with most occurring in the West. Since 2007, this is the third-largest to date in terms of burned acres.

Cliff and I agree the showers will return early next month, near the Oct. 5 “full moon” cycle. Also, we expect to see a big increase in moisture across our region with a series of Pacific storms by late October or November. Our current seasonal moisture stands at 27.42 inches and we think there’s a good chance we’ll end up near 40 inches at the end of the year.

Our first measurable snowfall of the season, in the lower elevations, may be as early as Nov. 5-10. But, the high mountain areas have already seen some of that white stuff and could start seeing measurable snow later next month. Stay tuned.

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Contact Randy Mann at randy@longrangeweather.com.