Record heat possible Labor Day weekend into early next week

September 3, 2020 – Smoke and haze from wildfires will continue to impact air quality and temperatures this week. Dry weather and above average temperatures expected through Friday.

Discussion

Upper level ridge will cause a gradual warming trend over the next couple of days, as onshore flow weakens. Much hotter conditions then return Saturday and Sunday with upper level high strengthening near the Great Basin Region. Dry weather with temperatures warming to from 4 to 8 degrees above normal at most locations today and Friday. Winds will remain light at most locations except near the Delta, where local gusts to 30 mph will be possible.

Main weather concern going forward will be another possible historic heat wave Saturday through Tuesday. Temperatures are expected to be from from 15 to 20 degrees above normal during this timeframe. High temperatures are forecasted to approach 110 degrees at Sacramento, Stockton and Modesto. These readings would break all-time September high temperatures records for these locations.

Also low temperatures are expected to be very warm only cooling into the 75 to 80 degree range. These extreme temperatures will cause dangerous heat impacts and an excessive heat watch will continue Saturday through Tuesday. There is the potential for very high heat risk during this time, which could impact the general population, especially those spending an extended time outdoors.

Extended Discussion (Monday through Thursday)

Very strong upper level ridge will be in place much of next week. This will keep above normal temperatures over Norcal with readings from 10 to 15 degrees above normal. If heading to the mountains for heat relief it will be limited, as mountain highs are expected to be in the 80s and 90s and they are included in the Excessive Heat Watch.

Also overnight lows will remain hot especially in the thermal belts. Please learn the symptoms of excessive heat exposure, stay hydrated and never leave children or pets unattended in vehicles.

Euro solution has come more in line with the past few GFS runs, which keep a bit more of a progressive pattern in place. This allows upper trough to drop down over the Rockies instead of retrograding west into Nevada with upper ridge remaining in place over northern California. This solution will lessen the threat of north winds and downslope east winds early next next week. Confidence will increase in the lesser wind scenario if a few more model runs show this, but would still rate the extended forecast confidence on the low side.