A building heat wave expanding across the West is going to produce some dramatic jumps in temperature today. A few interior Northwest and northern Rockies spots will see temperature rise 40 to 50 degrees today.

A dome of hot air producing several daily temperature records in excess of 110 degrees across the Southwest and Great Basin is expanding northward. High temperatures will be in the upper 90s well into eastern Washington, northern Idaho and western Montana.

The TemperatureRadar shows afternoon highs reaching the triple digits in places like Medford, Ore., Boise, Idaho, and Salt Lake City.

For many of these places, this morning's low temperatures are in the 50s and 60s, so today's temperature rise will rise 30 to 40 degrees as bright August sunshine beats down. As shown below, Pocatello, Idaho, will be one of several places that will experience a 50-degree temperature rise.

These extreme temperature changes occur when low humidity and clear nights allow temperatures to drop quickly after sunset followed by long summer days with full sunshine.

If you live in these area, be prepared for the extreme heat by staying hydrated, limit outdoor activities during the hottest time of the day and remember to check the UV forecast to avoid sunburns.