Portola Valley Warnings, Watches and Advisories

When a severe thunderstorm warning is issued, the storm may produce damaging winds, large hail, dangerous lightning, and heavy rain. In some cases, heavy rainfall produced by a severe storm can also lead to flash flooding. Do not drive vehicles through flooded areas. The water depth or fast flowing water/mud/debris from a flash flood will make road conditions unsafe. Do not rely soley on data presented here or other third-party websites - always check your official national and local weather service agency website, socials, radio and/or TV stations for making critical decisions related to weather events.

Please carefully read each posted Warning and Alert as it relates to the area(s) being affected. We may provide a wider range of issued severe weather warnings for surrounding cities and counties, so some alerts may not directly impact this location. This is done to help with preparing for severe weather that may overlap or be heading towards Portola Valley.

Use the Radar Maps link provided to understand the trajectory of a storm.

Red Flag Warning issued August 31 at 4:39AM PDT until August 31 at 8:00PM PDT by NWS Medford OR

* AFFECTED AREA...In California...The Scott Valley in Fire weather zone 280, Fire weather zone 281, Fire weather zone 284 excepting the southeast portion of the zone, and Fire weather zone 285. In Oregon...Fire weather zone 624, excepting the Highway 97 corridor from Modoc Point to Chemult. * WIND...South winds 10 to 20 mph with gusts to 30 mph in the Scott Valley, and 15 to 25 mph with gusts to 35 mph in the Shasta Valley. Elsewhere, southwest winds 10 to 20 mph with gusts to 30 mph. * HUMIDITY...Minimum humidity 9 to 15 percent. * DETAILED URL...View the hazard area in detail at https://weather.gov/wrh/hazards?wfo=mfr

Beach Hazards Statement issued August 30 at 1:16PM PDT until August 31 at 3:00PM PDT by NWS Los Angeles/Oxnard CA

* WHAT...Dangerous rip currents and breaking waves with isolated sets up to 6 feet due to elevated surf from southerly swells. * WHERE...Ventura County Beaches, Malibu Coast and Los Angeles County Beaches. * WHEN...Through Monday afternoon. * IMPACTS...There is an increased risk of ocean drowning. Rip currents can pull swimmers and surfers out to sea. Waves can wash people off beaches and rocks, and capsize small boats nearshore. * ADDITIONAL DETAILS...A series of southerly swells will continue to impact Southern California through much of next week.

Fire Weather Watch issued August 30 at 9:19AM PDT until September 1 at 11:00PM PDT by NWS Reno NV

The National Weather Service in Reno has issued a Fire Weather Watch for gusty winds and low humidity, which is in effect from Tuesday morning through Tuesday evening. * Affected Area...Fire Weather Zone 270 Surprise Valley California, Fire Weather Zone 278 Eastern Lassen County, Fire Weather Zone 420 Northern Sierra Front including Carson City, Douglas, Storey, Southern Washoe, Western Lyon, and Far Southern Lassen Counties, Fire Weather Zone 458 Northern Washoe County. * Winds...Southwest 15 to 25 mph with gusts 30 to 40 mph. * Humidity...As low as 10 to 15 percent. * Duration...3 to 6 hours. * Impacts...The combination of gusty winds and low humidity can cause fire to rapidly grow in size and intensity before first responders can contain them.