Hot and dry now, but wait 'til fall
I’ve been receiving emails asking when temperatures will finally cool down as the hot weather continues to drag on. Based on the current pattern, we’re expecting to see a brief end to the 90-degree temperatures as soon as late this week.
Since June 24, highs have been at or over 90 degrees at Cliff’s station in northwestern Coeur d’Alene. Of course, we’ve already had five days with highs over the 100-degree mark, which was the hottest late June period in recorded history.
As we get toward the end of the month and into early August, the Inland Northwest may see another round of hot weather with highs at least in the 90s and perhaps several more days with 100-degree readings.
Average temperatures last month were over 8 degrees above normal in Coeur d’Alene. Through the first week of July, the average readings were over 10 degrees above normal. It’s certainly been one of the hottest early summer seasons in history in Coeur d’Alene and the Inland Empire.
The latest information from the U.S. Drought Monitor has Coeur d’Alene on the edge of severe to extreme drought. Most of central and eastern Washington are in the extreme drought category, while large areas in the desert Southwest, as well as parts of California, are experiencing exceptional drought conditions.
The long-range computer models are continuing to show more dry weather across the western portions of the country. In fact, we don’t see much moisture in North Idaho for at least the next several weeks. Unless there is a relatively strong afternoon thunderstorm later in July, it appears that Coeur d’Alene will have its fifth month in a row with below-normal precipitation.
Since 2010, when Coeur d’Alene has a dry summer, the following fall is often wetter, in terms of percentages. For the 2018 and 2019 seasons, the summers were dry, but the fall of 2019 was also drier than average with the majority of the fall’s precipitation arriving in October. Last year, the summer was dry with near-normal precipitation, close to 100%, for the fall season.
The chart shows the percent of normal for the meteorological summer season, which begins on June 1 and ends on August 31. The normal precipitation for those three months is 4.08 inches. The meteorological fall season begins on Sept. 1 and ends on Nov. 30 and the normal moisture is 6.77 inches.
In 2016 and 2017, we had a pattern of a very dry June through August, followed by a wet fall. During those two seasons, there was a big month for moisture during the fall.
In 2016, for example, a total of 2.76 inches of rain fell during the summer, but 13.48 inches was reported from September through November, close to double the normal. Much of the moisture that fell was in October of 2016 as a record-smashing 8.88 inches was reported.
In 2017, only 1.31 inches of rain fell for the three summer months, but 9.19 inches moisture was measured during the fall season. November of 2017 was the big month that year with an above average total of 5.27 inches of rain and melted snow.
From 2012 through 2014, the summer seasons were wetter than normal in Coeur d’Alene and the fall seasons were close to normal. However, we’ve been in a pattern of drier than normal summers since 2016, and 2021 will likely follow this trend.
As of the weekend, only .49 inches of rain had fallen since June 1. Our average from June 1 through July 12 is about 2.80 inches, so we are less than 20 percent of normal moisture.
Since the start of the astronomical summer on June 21, there hasn’t been any measurable rainfall. Cliff and I don’t expect to see much moisture between now and the middle of August. However, we should start to see an increase of some rain later next month and into September.
With these extreme weather patterns, when we have extremely dry conditions on one side, we will often flip to the wetter side. Therefore, our chances for wetter than normal weather become much higher in October and/or November.
For 2021, we think that November will be a good one for moisture. It’s possible that the wet weather could start in October, but these patterns will often take more time to develop.
Regardless, Coeur d’Alene could receive at least 11 inches of moisture for the fall season, or about 170 percent of normal, especially if a new cooler than normal sea-surface temperature event, La Nina, starts forming late this year.
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Contact Randy Mann at randy@longrangeweather.com