In early July, we received a good taste of summer as temperatures across much of the Inland Northwest approached the 100-degree mark. The hottest day was July 1 with a high of 99 at the Spokane International Airport.
The heatwave came to an end in time for the Fourth of July. The strong high pressure ridge – a large dome of sinking air – that dominated our weather, bringing the sunshine and hot temperatures, weakened and allowed cooler air into the region.
Although the rest of this summer will be hot at times, I don’t expect to see this year rank in the top five in terms of heat and dryness. The warmest average temperature (includes both the high and low) for June, July and August occurred in 1922 with a reading of 71.3 degrees. The normal is 66.3 degrees.
The peak of our Earth’s temperature occurred in 1998 with an average reading of 59.3 degrees. That year was Spokane’s seventh-warmest summer at 69.9 degrees. During that time, there were 38 days at or hotter than 90 degrees, second only to 39 days in 1958 in Spokane. We also sweltered through four days at or more than 100 degrees in 1998.
The last time the airport hit the 100-degree mark was Aug. 1, 2009, with a high of 101 degrees. The hottest summer month was July 1960 with an average high of 91.5 degrees. Last year, the warmest day was July 8 with a reading of 98 degrees.
Between now and August, there should be more hot weather, but I don’t see four afternoons in a row in July with triple-digit readings as occurred in 2006, which was one of the driest summer seasons across much of the Inland Northwest.
One of the reasons why I’m looking for this warmer, drier than normal summer season is the La Niña sea-surface temperature pattern that has recently developed in the south-central Pacific Ocean. La Niña is the abnormal cooling of ocean waters near the equatorial regions. During this kind of pattern, we often see drier and warmer conditions in July and August.
If this weak La Niña phenomenon remains intact for the next few months, we may experience an earlier than normal start to fall. Moisture should start to increase by the middle of September. Stay tuned.