The forecast for the week ahead looks much warmer than normal, with clear skies and light onshore winds that could lift San Francisco temperatures well into the 80s.
A high-pressure system is expected to approach and then move over the region, compressing and reducing the usual marine layer's coastal breeze that usually helps the city keep its cool.
The system will bring drier, warmer air down from the state's north and inland, helping daytime temperatures to spike in neighborhoods south and west of Downtown like the Mission and SoMa.
Temperatures should still trail off into the upper 50s to lower 60s overnight during Thursday and Friday, the week's warmest anticipated days.
"If there's one silver lining to hotter temperatures this time of year, the nights are longer," National Weather Service meteorologist Sean Miller said Tuesday.
"It's going to be cooling off at night, though it may not be as cool as we have been the last few nights" with temperatures in the upper 50s to lower 60s, he said.
Increasing potential for 90+ temperatures on Thursday into Friday. Are you ready for hotter weather? Make sure to practice heat safety, check on others, and avoid strenuous outdoor activities during the afternoon hours. #cawx pic.twitter.com/NEYFgoC4HW
— NWS Bay Area 🌉 (@NWSBayArea) October 3, 2023
Miller recommended that residents and visitors limit any strenuous activity outdoors from noon to 6 p.m. and consider visiting stores, malls, libraries or other venues with air conditioning. He also said pet owners should avoid walking animals on hot sidewalks and keep them out of parked vehicles, which are likely to heat up fast with exposure to the sun.
Health experts and emergency services warn that excessive exposure to heat can cause illnesses as serious as strokes, exhaustion and cramps—all issues exacerbated by a lack of access to fans, air conditioning or adequate cooling areas.
Tuesday's highs will be in the low 70s, nowhere near San Francisco International Airport's record of 95 degrees set in 2014 or the 97-degree mark in Downtown San Francisco reached in 1985.
Wednesday should see sunny skies with highs in the 70s to lower 80s and light northeast winds up to 10 mph, yielding to mostly clear skies at night with lows in the lower 60s and winds swinging westerly.
Thursday and Friday's weather will be similar but should push high temperatures well into the mid-80s before easing back to the lower 80s Saturday. Cloudy skies and cooler temperatures will return Sunday and Monday, with highs ranging from the upper 60s to lower 70s.