Heat Dome to Set Records in the West Much of This Week

 Chris Dolce

Published: June 15, 2021

Dangerously hot temperatures will grip parts of the West this week, smashing numerous daily record highs and even threatening a few all-time June records.

A large dome of high pressure in the upper atmosphere has developed over the West. Beneath the dome, sinking air is causing temperatures to soar well over 100 degrees in many areas.

Heat alerts have been issued by the National Weather Service for various time periods this week, from parts of the Southwest into the Great Basin and California, as well as into parts of Montana. Outdoor activities should be limited in these areas because of the possibility of heat-related illnesses.

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The core of the heat will be most persistent in the Southwest, but it will also affect parts of the Great Basin and Rockies. It will spread into California's central valley later in the week.

(MAP: Current Temperatures)

Records have already been broken in this heat wave and more are likely to fall in the days ahead, from Montana into the Desert Southwest and California.

Salt Lake City broke daily record highs on Sunday (102 degrees) and Monday (103 degrees), then tied its hottest June temperature on record Tuesday (105 degrees).

Tucson, Arizona, set a daily record high for the third consecutive day on Monday.

Monday's high in Helena, Montana, hit 104 degrees, marking the earliest in the year on record the city has been 100 degrees or hotter.

Billings, Montana, Denver, Salt Lake City, Phoenix, Las Vegas and Sacramento are some of the cities that could set at least daily record highs in the week ahead.

Some locations could even threaten all-time record highs. This includes Salt Lake City and Las Vegas, where the all-time records are 107 degrees and 117 degrees, respectively.

Forecast Highs

The hot conditions this week will be particularly dangerous for vulnerable groups, such as the sick and the elderly. The NWS has useful heat safety tips that can be incorporated into a daily routine when extreme heat sets in.

• Job sites: Stay hydrated and take breaks inside as often as possible. Remember that in temperatures above 110, you will not know that you are sweating.
• Indoors: Check up on the elderly, sick and those without air conditioning.
• In vehicles: Never leave children or pets unattended – look before you lock.
• Outdoors: Limit strenuous activities and find shade. Drink plenty of water and avoid alcohol.

Wildfire concerns will also be elevated this week because of the hot temperatures in combination with long-term drought conditions in place across a large part of the West.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.