Another Extreme Heat Event Ahead for the West

Highlights: Next hot event in California is historic and extends to the Northwest States.

Fig. 1: Spaghetti plot of max/min forecasts using all models highlighting the extreme heat risk for early next week in Redding, CA.

Discussion: Super heatwave no. 1 across California and the Desert Southwest has ended. All eyes are on the next one which will be stronger.

This week simmers to near normal although the San Joaquin Valley remains borderline hot the next 2 days. Wednesday is the most temperate day this week. Coastal areas receive excellent cool (marine) relief.

However, beginning Friday hotter weather begins to return. Coastal areas are still OK while the San Joaquin Valley heats to 101-108F. On the weekend 80’s and some 90’s will reach the central and especially the southern coast of California while inland readings of 105-120F are common. The 120+F risk is for the northern San Juaquin Valley and would break all-time records (Fig. 1).

Early next week is the peak of the heat timeframe at which time some models indicate 123-124F in the northern San Joaquin Valley (Fig. 2). Interior Washington/Oregon could also see all-time record hot 120F! The super extreme heat will not reach the California Coast.

Fig. 2: GFS maximum temperature forecast for next Monday indicates widespread 110’s with two zones of >120F.

Excessive Heat Warning extends to the southern California coast. Temperatures at the coast and reach 90F while inland readings extend to the 110’s. The excessive heat watch in effect for the San Juaquin Valley shifts to a warning by tomorrow as near 110F evolves for mid-to-late week. For the moment, the excessive heat is not forecast to reach the central and north coast of California.

Heat wave no. 2 winds down by the middle of next week.