A relentless heat wave is slowly building across the Western U.S. through Mother’s Day weekend — and the hottest day is still ahead. Here’s exactly what to expect, city by city.
If you’re in the West, the phrase “it’ll cool down tomorrow” isn’t going to help you this week. Temperatures are climbing day by day in what forecasters are calling a “slow boil” — not a sudden spike, but a steady, suffocating build that peaks on Tuesday before gradually easing back.
How bad will it get, exactly?
Monday brings the first real punch. Most of the Intermountain West and Northwest will hit the 80s and 90s. The Desert Southwest — think Las Vegas, Phoenix, Palm Springs — climbs into the mid-100s. But that’s just the opening act.
| Las Vegas 107°F | Boise 95°F | Salt Lake City 93°F | Denver 84°F |
| Portland 79°F | Seattle 75°FBillings 82°F | Billings 82°F | Pacific Coast ~65°F |
“Tuesday is the day to watch. That’s when the heat peaks from the Northwest all the way down through the Rockies — and the Desert Southwest remains locked in triple digits.”
What’s actually causing this?
The science here is straightforward: a strong ridge of high pressure has parked itself over the West, pushing the jet stream northward. Everything sitting south of that jet stream bakes under clear skies and sinking, warming air. The stronger the ridge, the hotter the temperatures — and while this system isn’t breaking pressure records, its size and persistence are what make it stand out.
If you’re searching for a cool escape, head to the Pacific Coast. The cold offshore waters are acting as a natural air conditioner, keeping highs pinned in the 60s to near 70°F — a nearly 40-degree difference from inland desert cities.
When does relief finally come?
The honest answer: not dramatically soon. Temperatures will dip after Tuesday, but they’ll remain above seasonal averages for the rest of the week. The ridge is expected to shift eastward, which means the West will gradually moderate heading into next week — while the central and eastern U.S. may start feeling the warmth instead.
Longer-range forecasts from the Climate Prediction Center do show a return to more normal temperatures across the West in the weeks ahead, so there is light at the end of the tunnel — it’s just a hot, slow walk to get there.
