Phenomena: Extreme Heat/Heat Dome
Satellite: GOES-18 (GOES West)
Product: Water Vapor
Instrument: Advanced Baseline Imager
Timespan: March 18, 2026, 00:30-19:20 UTC
As record heat bakes the western U.S. this week, NOAA’s GOES West satellite tracked the atmospheric setup for this extreme heatwave. In this water vapor imagery from March 18, you can see how the satellite captures the deep moisture (shades of blue) surging northward as a large area of high pressure settles into the Southwest.
In the Northern Hemisphere, areas of high pressure rotate clockwise, with sinking air that compresses and warms as it descends to Earth’s surface. When an area of persistent high pressure occurs over a location, it can trap heat close to the ground for a prolonged period—causing a “heat dome” that drives record-breaking temperatures.
According to the National Weather Service Weather Prediction Center, “Numerous and widespread daily and March monthly record highs are likely [this week], with some locations in California already breaking their March monthly records on Tuesday. Many locations across the Desert Southwest are expected to see their earliest 100+ degree day on record.”
On Tuesday, March 18, several cities set new records: Phoenix’s Sky Harbor Airport reached 101 degrees F at 2:59 pm MST, setting a new record high temperature for the month of March. Flagstaff, Ariz., with an elevation of more than 6,800 ft., hit a March record high of 76 degrees. Las Vegas sweltered under an all-time March record high temperature of 94 degrees, as downtown Los Angeles baked under a daily record high of 95 degrees.
NOAA’s GOES West geostationary satellite, also known as GOES-18, provides geostationary satellite coverage of the Western Hemisphere, including the United States, the Pacific Ocean, Alaska and Hawaii. First launched in March 2018, the satellite became fully operational in February 2019.