National Weather Service San Francisco CA 505pm PDT Fri Jun 28 2024
.SHORT TERM... (This evening through Saturday) Issued at 313pm PDT Fri Jun 28 2024
Low clouds persist along the Monterey coastline with stratus expected to return inland overnight along the Central Coast and up the coast of the SF peninsula. Widespread minor heat risk and patches of moderate heat risk over the North and East Bay continue through Saturday. Overnight temperatures Friday into Saturday will largely be in the mid 50s to low 60s. A slight warming trend is expected to kick off Saturday and Sunday before the more substantial warming anticipated next week. High temperatures on Saturday will warm slightly (2 to 4 degrees on average) with inland highs largely in the 80s to low 90s. Favored hotspots in the North and East Bay may reach the mid 90s. Closer to the coast, cooler temperatures prevail with highs in the low to mid 60s. Given the long term trend for warmer, excessively dangerous heat next week - make the most out of these comparatively cooler temperatures and take care of any outdoors activities you may need to do this weekend.
Long Term
(Saturday night through next Thursday) Issued at 313pm PDT Fri Jun 28 2024
A weak warming trend continues through Sunday with temperatures similar to Saturday in the 80s to low 90s expected. The main story for our long term forecast: a strengthening surface high pressure system and a large upper level ridge will move inland and bring dangerously hot, well above average temperatures for all areas away from the coastline in the Bay Area and Central Coast. This will be a prolonged heat event beginning Monday and continuing through the end of the week with widespread major to extreme heat risk expected over the majority of the Bay Area and Central Coast. An Excessive Heat Watch has been issued beginning Tuesday morning (when widespread major to extreme heat develops) through Friday evening. Wondering what an Excessive Heat Watch is? An Excessive Heat Watch is issued when dangerous heat is possible in the coming few days. An Excessive Heat Warning is when dangerous heat is currently occurring or about to start occurring. For now, we are still in the watch phase but everyone should start preparing for the excessive heat next week by rescheduling any outdoors activities and having a way to access somewhere that has A/C (for more ways to prepare see Heat Safety and Impacts section below).
Getting into the gritty details of what we know so far:
High temperatures will warm into the upper 80s to upper 90s beginning Monday with moderate heat risk expected over much of the Bay Area and Central Coast. Tuesday will mark the beginning of widespread excessive, dangerous heat with high temperatures breaching the mid 90s to low 100s. Across favored hot spots in the North/East Bay and portions of interior Monterey and San Benito Counties high temperatures may reach up to 110 degrees with extreme heat risk forecast for these areas. Overnight temperatures are not spared from this warming trend with widespread overnight lows in the upper 50s to mid 60s. In areas where extreme heat risk is expected, overnight low temperatures will be in the upper 60s to in the 70s. Longer term guidance (beyond this forecast period) suggests that anomalously warm temperatures may persist past Friday into next weekend. We will continue to monitor this as we get closer to the event.
Daytime relative humidity values will drop beginning Tuesday through the end of the week with widespread daytime RH values in the mid teens to mid twenties across the interior. For most areas there will be fair to good overnight relative humidity recoveries (60-70%) while portions of interior North/South/East Bay and interior Monterey/San Benito county may see locally poorer overnight relative humidity recoveries (20-40%). This will bring elevated fire weather concerns across interior portions of the North/East/South Bay with emphasis placed on the interior North Bay Mountains and far interior East Bay Hills. Remember, we have had several fires already this fire season so fine fuels (grass, shrubs, etc.) are already dry and ready to burn. Given that Fourth of July takes place in the middle of this heat wave take GREAT care with any outdoor activities involving barbecues, sparks, or any sort of flame.
One last thing to note - we are entering the King Tide cycle beginning this week with minor coastal flooding possible in Bayside portions of the North Bay and along the Embarcadero in San Francisco.
Heat Safety and Impacts:
By now you’re well aware that it is going to be extremely hot next week with well-above normal temperatures; now lets talk about the impacts of excessive heat and actions we can take to minimize those impacts: With extreme heat, and especially prolonged heat events, it is a marathon, and not a sprint. Our bodies, infrastructure, pets, and livestock will be under duress from heat over the span of days as opposed to just a day or two. Given that there is little overnight relief expected throughout this event, this is where it really becomes a marathon, and precautionary measures are necessitated in order to prevent adverse results such as heat exhaustion and stroke. This is not just for individuals sensitive to heat, but rather, the entire population. Heat for this duration and at these temperatures can be dangerous for everyone. Do your body a favor and if you can, suspend outdoors activities between the hours of 10am and 7pm on days where Excessive Heat Watches or Warnings are in effect. Remain in air conditioning if you have that available to you in your residence, or seek out air conditioned environments such as stores, movie theaters, restaurants, libraries, and cooling shelters.
If you cannot access air conditioned environments, must be outside, work outdoors, or otherwise, there are other precautionary measures you can take to keep yourself and your loved ones safe (including pets!) during excessive heat. Take frequent breaks in the shade and ensure that you are drinking plenty of cool water, or other hydrating beverages such as sports drinks with electrolytes. Avoid DEHYDRATING drinks such as alcohol or caffeinated beverages. That aside, visiting your city public pool or a lake, river, or ocean can also help keep you cool, but don’t forget the life jacket! If planning on swimming, stick to where there is a lifeguard, and know the ocean or river conditions before you get in. Although outside of our area, its worth repeating: rivers can run fast and cold with snowmelt in the Sierra Nevada mountains, and cold water shock can set in quickly, which can lead to loss of muscle control, and ultimately, drowning. Cold water shock can also set in for ocean- goers. Have fun at the water, but be smart, be safe, and Know Before You Go!
Finally, if you do not have air conditioning or cannot access it, and also cannot access a body of water to stay cool: consider taking cold showers or baths, turn on those sprinklers or garden hose and have a fun time in your own makeshift “water park,” or lay a damp, cool towel across your head or body. Even just dipping your hands and feet in cool water can help to abate feelings of excessive heat. For pets and livestock, make sure they have access to shade structures or areas, and have clean water freely available to them at all times. They do not have the same resources or ability to notify of feeling heat-stressed as we do, so check in on them! If they’re permanently outdoors, consider giving them a quick rinse- down with the hose or set up misters, as the evaporation will help to keep them cool as well.
Marine
(Tonight through next Wednesday) Issued at 420pm PDT Fri Jun 28 2024
Breezy to gusty northwesterly winds continue into next week before diminishing to more moderate winds. Significant wave heigheights begin to build to 10-12 feet towards the beginning of next week. Light southerly swell continues to move through the waters alongside moderate northwesterly swell.
Fire Weather
Issued at 322pm PDT Fri Jun 28 2024
Temperatures will hover right around seasonal averages through the weekend with relatively light onshore breezes. There is an Excessive Heat Watch in effect across our area for Tuesday through Friday of next week, encompassing the Fourth of July holiday. Confidence is increasing for an unusually strong dome of high pressure across our region that will produce daily maximum temperatures well above normal and subsequently, very low min RH values. The building heat will also result in poor overnight RH recovery. Please plan accordingly.
NOAA San Francisco Bay Area Office: Watches - Warnings - Advisories
CA...Excessive Heat Watch from Tuesday morning through Friday evening for CAZ502>504-506-508-510-512>518-528.
PZ...Small Craft Advisory until 3am PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory from 9am Saturday to 9am PDT Sunday for Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory from 3pm Saturday to 9am PDT Sunday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9am PDT Sunday for Pt Arena to Pt Reyes 10-60 NM.
