From NWS:
The upper level pattern to start the first full week of September features an intensifying ridge in the West with a pair of upper troughs tracking across the northeastern quarter of the Lower 48. The hottest temperatures will be centered over the western third of the country with high temp departures ranging between 10-20 degrees above normal. Some locations in the Desert Southwest are under Excessive Heat Warnings due to daytime highs forecast to range anywhere from 105-115F with some spots even surpassing 115F. Heat Advisories are also in effect for much of California's Great Valley and a large chunk of Southern California. By Tuesday the heat continues to build even more in the Great Basin and Intermountain West where a handful of daily record high temps could be tied and/or broken. The large area of high pressure aloft will keep the West dry as well, meaning little relief is expected to come for ongoing wildfires. In fact, there are Elevated Risks for favorable fire weather conditions in the northern Rockies and High Plains. Expect large swaths of wildfire smoke to blanket much of the West and parts of the Plains with some Air Quality Alerts posted from the West Coast to the Rockies.
