San Francisco Bay Area residents are advised to stay hydrated and find shade as the National Weather Service (NWS) extends its heat advisory until Friday at 8 PM. According to NWS, this heat advisory is a relief after temperatures in inland areas were significantly higher last week. With an Excessive Heat Warning also in effect for parts of the region, individuals vulnerable to heat should take extra precautions to avoid heat-related illnesses.
Bracing to mitigate the ongoing inland heat wave, which has seen its seventh day, the Bay Area will experience a temperature decline through Tuesday before the mercury rises again mid-week. In a move designed to reflect the decreased risk associated with lower temperatures accurately, the Excessive Heat Warnings have been downgraded to Heat Advisories for various regions. "Monday will be another 5 degrees cooler than Sunday was", the NWS noted in their Area Forecast Discussion. However, they cautioned the public by extending many of the new Heat Advisories through Friday.
The forecast bears a hint of uncertainty starting Wednesday. The stubborn ridge responsible for high temperatures slowly shifts eastward, but the incoming zonal jet stream flow is anticipated to bring warmer conditions again to inland areas. "While the ridge leaving is certainly a good thing to help end this heat wave, the new pattern with higher pressure inland could support offshore winds later in the week", the NWS explained. This would temporarily reverse the current cooling trend, with expected temperature increases of approximately 10 degrees from Tuesday's highs.
Looking toward the weekend, the NWS predicts a more substantial cooling period, which may bring temperatures down to seasonal norms by the middle of the following week. But it's not a straightforward path to cooler days. The weather models, namely Global Forecast System (GFS) and European Centre for Medium-Range Weather Forecasts (ECMWF), are at odds beyond the weekend—with the GFS leaning cooler and the ECMWF holding steady. As per the forecast, "this week will be cooler than last week, and next week will be cooler than this week." Even so, Bay Area residents may contend with above-normal temperatures after all the anticipated cooling.
Marine conditions also adapt to the heat, with gentle to moderate west to northwest winds expected early in the week. However, the NWS Marine Outlook warns of a fresh return to strong northwest winds across coastal waters by Wednesday, leading to significant wave heights of 10-14 feet by the week's end. Coastal mariners should exercise caution and monitor updates. As for aviation, Bay Area and Central Coast airports will likely see morning stratus clearing. Still, they should prepare for its return in the evening, affecting visibility conditions and potentially necessitating further advisories.
