Another heat dome in the West producing dangerous temperatures

 By Jessica Storm, AccuWeather Meteorologist

Updated Jul. 18, 2021 3:30 AM PDT

Record-challenging heat will continue baking the Rockies, northern Plains and Canadian Prairies through early this week. Even before the heat wave got underway, temperatures have been above average since early last week. Residents can't catch a break from the heat after records were challenged on Saturday.

Billings, Montana, among other cities, rose into the 100s on Saturday, tying the July 17 record temperature of 101 degrees Fahrenheit originally set in 1937. Typically in July, Billings will have temperatures in the upper 80s.

On Saturday, Missoula, Montana, reached 90 F, which marked the 21st consecutive day of temperatures 90 or higher. This breaks the all-time record set in August 1904, according to the National Weather Service (NWS) of Missoula.

"A large dome of high pressure will continue to bring extreme heat across the northern Rockies and northern Plains on Sunday and into the middle of this week," said AccuWeather Senior Meteorologist Robert Richards.

This heat dome can thrust temperatures 10 to 20 degrees above average in some locations, with some places reaching triple digits.

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"Cities like Billings and Bismarck, North Dakota, will experience dangerous heat," said Richards. Records will be challenged across this part of the country.

"Billings will challenge a record high on Sunday and on Monday," said Richards. The record high for July 18 is 104 set in 1955, while the record for July 19 is 105.

"Bismarck will challenge record highs on Wednesday and Thursday when the core of the heat moves into the northern Plains and out of the northern Rockies," said Richards. Bismarck's record on Wednesday is 104 set in 1921 and on Thursday is 103 set in 1901.

Parts of southern Canada will also be under fire during this intense heat event, including parts of Alberta and Saskatchewan. Regina, Saskatchewan, is expected to have temperatures in the lower 90s (32 to 34 degrees Celsius) on Sunday and Monday, while the city usually sits in the upper 70s (24 to 25 C) this time of year.

Excessive heat warnings and heat advisories are in effect across parts of Idaho and Montana, impacting Boise, Idaho, and Helena and Havre, Montana. Heat warnings and air quality statements run from southeastern British Columbia to Ontario in Canada.

If residents stay out too long in this extreme heat, this can lead to heat exhaustion, according to Richards. Heat exhaustion is the precursor to heatstroke and is a direct result of the body overheating. If heat exhaustion is not addressed, there is the risk for heatstroke.

Vital heat safety measures to avoid this include staying hydrated, staying indoors in an air-conditioned room if possible and limiting strenuous outdoor activities. Overactive air conditioners due to this event can put a strain on the power companies and electric bills.

The National Weather Service (NWS) of Billings posted a temperature recording of 126 F inside a parked car on Saturday, emphasizing "Never leave a child or pet inside a parked car."

Smoky conditions are also expected to continue through Monday, depending on the status of local fires, including the Bootleg Fire, Elbow Creek Fire, Trail Creek Fire and Sugar Fire. Air quality alerts are in effect across the region, including in Burns, Oregon; Lewistown, Idaho; Omak, Washington; and Denver.

Monsoon storms are also headed to the interior Northwest, bringing dry lightning, which can spark more smoke-producing wildfires across the drought-stricken region. Over 60% of the West is in extreme drought, according to the United States Drought Monitor.

Temperatures will generally fall short of the century mark on Tuesday forward in most areas, but will remain above average and mostly in the 90s through the rest of the week.

There is the chance for some monsoon moisture to bring rainfall across the Four Corners states, possibly into the Great Basin and southern interior Northwest, which may decrease temperatures next week, according to AccuWeather Senior Meteorologist Tyler Roys.

However, the heat dome is expected to remain in the Plains and even expand. Temperatures and rainfall will greatly depend on the position of the high pressure throughout next week.

Related:

Dangerous combination of drought and dry lightning to set up in the northwestern USWildfires rage throughout western North AmericaHeat exhaustion vs. heatstroke: What are the warning signs and how should you react?Preventing Heat-Related Illness: When the Heat Is Too Hot to Handle

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