A record-breaking early September

Last week was the hottest early September period in Coeur d’Alene’s history, dating back to 1895. The first three days of the month had temperatures at or above 100 degrees at Cliff’s station. Two of the three days were record-breakers as a sizzling 103 degrees was reported Sept. 2.

During that very hot afternoon, the warmest readings were away from the lake as there was very little wind. However, near the lake, such as North Idaho College, high temperatures Sept. 2 were in the mid to upper 90s. The outlying areas were also very hot. It was 102 at Post Falls and Hayden, 103 degrees at Kellogg, 104 degrees at Dalton Gardens and Rathdrum, with a sizzling 105 degrees at Athol.

The latest 100-degree day on record in Coeur d’Alene during the month of September occurred Sept. 4, 1938, with a high of 101 degrees. In terms of 90-degree days, the latest one on record was Sept. 26, 1963, with a high of 90 degrees.

With the recent heatwave, there were a total of 34 days with high temperatures at or above 90 degrees in Coeur d’Alene. We also had three consecutive days with high temperatures of 100 degrees or higher. The large percentage of 100-degree days will occur from late June through August. This is the first time in recorded history that Coeur d’Alene experienced three days above 100 degrees in September.

Our average high temperature for the 2025 summer season to date is 85 degrees. It’s not the hottest summer season, but the cooler temperatures and some much-needed rainfall are expected this week. However, there are indications of more very warm weather next week.

Last year was another hot summer across the Inland Northwest. The summer of 2024 was not only one of the hottest in the region, but most of the U.S. as well. Record-breaking temperatures led to numerous blackouts and train delays as the tracks overheated and warped, especially in the southwestern part of the country. Our average high temperature during the summer of 2024 was 85 degrees.

The hottest summer season ever recorded in our region was back in 1967. This egg-frying summer had an incredible 16 afternoons above the century mark. There were likewise another 29 days with readings at 90 degrees or above. The average daily maximum temperature was 91 degrees, a full nine degrees above the normal (mean) maximum of 82 degrees. That year had September’s warmest day in Coeur d’Alene of 102 degrees that occurred Sept. 1, 1967. That record held up until last week when a sizzling 103 degrees was reported.

The second hottest summer was in 1961. The red-hot summer of 1961 was the only other summer season, besides 1967, with an average maximum reading above 90 degrees at 90.6 degrees. There were 15 afternoons of temperatures at or above 100 degrees, second only to 1967. The hottest temperature ever observed was a torrid 109 degrees set Aug. 4, 1961. There were an additional 28 afternoons above 90 degrees during the June 21 to Sept. 22 period.

The June through August precipitation was the least in recorded history in Coeur d’Alene. The three-month total was a mere 0.38 inches at Cliff’s station. In 2024, the June through August period had 2.53 inches. However, 1.11 inches of rain fell June 3 and 4 during that year. In 2021, it was another dry June through August with 1.94 inches of rain. The normal for the three months is 5.22 inches.

The weather pattern over the summer season has seen drought conditions over the western U.S., with deadly flooding in areas east of the Rockies. It was also an unusually humid summer season as warm and moist air moved in from the Gulf and Atlantic regions. Major cities like Chicago were hit with a 1,000-year rainfall event from Aug. 16-19. The subway tunnels in New York City were suddenly flooded when 4-7 inches of rain fell in just one hour July 14.

In addition to the heavy rainfall, some cities and towns near the Great Lakes along the Canadian border had low temperatures drop into the 30s last week. Historically, the wet weather patterns in the central and eastern U.S. will eventually “back up” over the western U.S. Assuming this long-term trend continues, after a dry summer, the odds are very good for above normal moisture for the Pacific Northwest later this year. This new pattern could begin as early as late September, but more likely in October or November. December is another month that we could see higher than average moisture. With the potential development of a new La Niña by late this year, as we’ve been mentioning, the odds for higher-than-average snowfall across the Inland Northwest, especially in the higher mountains, are much better this upcoming winter season. Stay tuned.

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Contact Randy Mann at [email protected].