It’s been a very hot end to the week and that will persist into the start of this new week as an upper-level ridge of high pressure continues to allow for above average temperatures. On Thursday, which was the first day of astronomical summer, Death Valley topped off at 126 degrees, making it the hottest first day of summer in recorded history, which seems quite fitting. That broke the previous record high of 125 degrees from 1961.
It’s somewhat fitting that @DeathValleyNPS set a new record high temperature on the first day of Summer – 126°F
Previous record was set way back in 1961 with 125°F#cawx
— NWS Las Vegas (@NWSVegas) June 22, 2018
This Sunday, temperatures will be variable across the region, ranging from up to 30 degrees above average from the Pacific Northwest through the Central Valley while temperatures are up to 10 degrees below average across extreme-southern California into southern Arizona. It will also be cooler than normal in Utah and Colorado. This will translate to actual high temperatures from the 80s and low 90s in the Pacific Northwest up to the 90s and 100s in the Central Valley of California. 100s and 110s will be commonplace in the desert Southwest, although Phoenix may struggle to hit 100 degrees, so a record low maximum is appearing likely to be broken. All remaining locations will generally be in the 80s, but the immediate West Coast will be in the cool 60s and 70s thanks to the influence for the cooler ocean waters.
On Monday, an incoming trough of low pressure will allow for the Pacific Northwest to cool off while the heat dominates across the southwestern US. Most areas will be near to up to 10 degrees above average. Parts of the Sierra Nevada into the state of Nevada will be up to 30 degrees above average. This will translate to widespread high temperatures in the 90s and 100s across the region.
The intrusion of the cooler than normal temperatures will persist across the northwestern US on Tuesday. Meanwhile in the Southwest, it will remain mighty hot with temperatures at levels of generally 5 to 15 degrees above average with the exception of the immediate West Coast. Once again, most areas can expect highs either in the 90s or 100s; parts of the desert region will rise into the 110s.
On Wednesday, the heat will nudge a bit to the north, working into Oregon while Washington remains cool. Temperatures will remain a 5 to 15 degrees above average in most areas, which means actual high temperatures will be in the 90s and 100s for another day in a row. In the Pacific Northwest, it will feel very comfortable with highs in the 70s and 80s. The only locations where highs will only be in the 60s in the Southwest in along the coast and into the peaks of the Sierra Nevada mountain range.
By Thursday, the heat will begin to erode thanks to a more extensive trough coming in from the Pacific Ocean, Temperatures will be below average across the Northwest and immediate West Coast while the rest of the region will be a few degrees within average. Highs will generally be in the 60s and 70s in the Northwest up to the 90s and 100s across much of the Southwest.