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Record Fall Heat in the U.S. and Canadian High Plains

By: Christopher C. Burt, 7:53 PM GMT on September 26, 2014

Record Fall Heat in the U.S. and Canadian High Plains

Temperatures on Thursday and Friday, September 25-26, soared to record levels for this time of the year in Montana, Wyoming, western North Dakota, and the south-central Canadian Plains. Here are a few details.

After a relatively cool summer, an early fall heat wave engulfed the U.S. and Canadian High Plains on Thursday sending temperatures close to 100°F in North Dakota and Montana. The hottest reading observed was 98°F (36.7°C) at Terry, Montana and also at Wasta, South Dakota. Miles City, Montana and Williston, North Dakota both reached 97°F (36.1°C), their hottest temperatures ever observed during the fall (post September 22nd) and for so late in the year. Poplar, Montana also reached 97°F. Most sites in Montana broke or at least tied daily record highs on both September 24th and 25th, as was the case in Livingston (91°F/32.8°F) on the 25th, Helena (91°F/32.8°C) on both the 24th and 25th, Cut Bank (90°F/32.2°C) on the 25th, Missoula (92°F/33.3°C) on the 24th, Kalispell (89°F/31.7°C) on the 24th, Butte (85°F/29.4°C) on the 24th, and Bozeman (91°F/32.8°C) on the 25th. What was truly remarkable was how the warmth engulfed the entire (very large) state of Montana with warmer than normal temperatures even for mid-summer.

Temperature table for September 25th at all the first-order NWS sites in the state of Montana. This, most likely, was the warmest fall day on record for the state. Table from NWS-Billings.

Northern Wyoming also shared the heat with Sheridan measuring a record on the 26th with a 94°F/34.2°C reading. This is their hottest temperature ever measured for so late in the season (93° has been observed as late as Oct. 1st in 2011). Worland was the warmest site in the state on the 25th with a reading of 94°F/34.4°C. The highest temp on Friday, September 26th will be higher than this. I'll update on Saturday when the data comes in.

A sample of some of Wyoming's record high temperatures the past few days. This table is just for the NWS-Riverton forecast area so does not include Sheridan which is in the NWS-Billings forecast region. Table from NWS-Riverton.

Western North Dakota also entered record-heat territory on the 25th as the 97°F figure at Williston indicated. That was the warmest location in the state but Bismarck and Minot both reached a summer-like 93°F/33.9°C.

In South Dakota the top temperature observed on the 25th was 98°F/36.7°C at Wasta. Rapid City peaked at 92°F/33.3°C, just 1°F shy of a record high for the date (which was 93°F/33.9°C back in 1894) but an amazing figure when one considers that just two weeks previously the city measured its earliest snowfall on record with a 1.6” accumulation on September 11th! UPDATE: Rapid City reached 95°F (35°C) on Friday September 26th, tying its record for the date.

Temperature records set in South Dakota on September 25th and 26th. Table from NWS-Rapid City.

Map of high temperatures reported on September 25th. Outside of the desert Southwest, Montana and North Dakota reported the highest temperatures in the nation. Map courtesy of Jonathan Erdman at The Weather Channel.

In Canada, Esteven, Saskatchewan hit 34.3°C (93.7°F) and Brandon, Manitoba 34.0°C (93.2°F). Both sites are near 50°N latitude so it goes without saying that these were the warmest temperatures ever observed for so late in the year at those sites. Jonathan Erdman at The Weather Channel pointed out that these temperatures were actually warmer than any location in Texas (93°F/33.9°C at Cotulla) for September 25th. Regina, the capital of Saskatchewan reached 33.1°C (91.6°F). Amazingly, this was the hottest temperature measured so far this year in the city! UPDATE: The 90°F (32.2°C) isotherm pushed as far north as Swan River, Manitoba (52° 07’ N) where on Friday, September 26th 35.1° (95.2°F) was observed. This may be the hottest temperature ever measured so far north so late in the year on the North American continent. The average high temperature for Swan River on September 26th is 60°F.

Jakarta, Indonesia Observes its Hottest Temperature on Record

While on the topic of heat records, it is worth noting that Maximiliano Herrera has informed me that Jakarta, Indonesia’s largest city, measured a temperature of 37.0°C (98.6°F) on September 24th at the Jakarta Observatory. This is the hottest temperature ever recorded in the city (records began in 1866 when Jakarta was named Batavia) and ties the record from any of the airport sites in the greater metropolitan area.

Christopher C. Burt
Weather Historian

Extreme Weather Heat

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.