Sunnyvale, CA Warnings, Watches and Advisories

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 Sunnyvale.

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

Heat Advisory issued July 14 at 12:27PM PDT until July 14 at 11:00PM PDT by NWS Sacramento CA

* WHAT...High temperatures up to 95 to 105 expected today. Widespread Moderate HeatRisk, with a few areas of Major HeatRisk. * WHERE...Burney Basin / Eastern Shasta County, Central Sacramento Valley, Mountains Southwestern Shasta County to Western Colusa County, Northeast Foothills/Sacramento Valley, Northern Sacramento Valley, Shasta Lake Area / Northern Shasta County, and Western Plumas County/Lassen Park. * WHEN...Until 11 PM PDT this evening. * IMPACTS...Heat related illnesses increase significantly during heat events, particularly for those working or participating in outdoor activities.

Extreme Heat Warning issued July 14 at 11:40AM PDT until July 15 at 8:00PM PDT by NWS Medford OR

* WHAT...High temperatures of 100 to 105 expected, except up to 110 in the valleys of western Siskiyou County. Low temperatures will be mainly in the mid to upper 60s. * WHERE...In California, Central Siskiyou County and Western Siskiyou County. In Oregon, Eastern Curry County and Josephine County and Jackson County. This includes the Rogue, Illinois, Scott, Shasta and Klamath River Valleys as well as the communities of Medford, Grants Pass, Ashland, Cave Junction, Yreka, Montague, and Happy Camp. * WHEN...For the Extreme Heat Warning, until 8 PM PDT Tuesday. For the Heat Advisory, from 8 PM Tuesday to 8 PM PDT Wednesday. * IMPACTS...An increased chance of heat related illness for those without access to cooling facilities. * ADDITIONAL DETAILS...Warm overnight temperatures will limit relief from hot daytime temperatures.

Heat Advisory issued July 14 at 11:40AM PDT until July 15 at 8:00PM PDT by NWS Medford OR

* WHAT...High temperatures of 95 to 100 are expected. Low temperatures will be mainly in the mid-50s to low 60s. * WHERE...Lake County and eastern Klamath County, South Central Siskiyou County, North Central and Southeast Siskiyou County, Northeast Siskiyou and Northwest Modoc Counties, Modoc County, and Klamath Basin. This includes Klamath Falls, Lakeview, Mount Shasta, and Alturas. * WHEN...Until 8 PM PDT Tuesday. * IMPACTS...An increased chance of heat related illness for those without access to cooling facilities. * ADDITIONAL DETAILS...Warm overnight temperatures will limit relief from hot daytime temperatures.

Heat Advisory issued July 14 at 11:40AM PDT until July 16 at 8:00PM PDT by NWS Medford OR

* WHAT...High temperatures of 100 to 105 expected, except up to 110 in the valleys of western Siskiyou County. Low temperatures will be mainly in the mid to upper 60s. * WHERE...In California, Central Siskiyou County and Western Siskiyou County. In Oregon, Eastern Curry County and Josephine County and Jackson County. This includes the Rogue, Illinois, Scott, Shasta and Klamath River Valleys as well as the communities of Medford, Grants Pass, Ashland, Cave Junction, Yreka, Montague, and Happy Camp. * WHEN...For the Extreme Heat Warning, until 8 PM PDT Tuesday. For the Heat Advisory, from 8 PM Tuesday to 8 PM PDT Wednesday. * IMPACTS...An increased chance of heat related illness for those without access to cooling facilities. * ADDITIONAL DETAILS...Warm overnight temperatures will limit relief from hot daytime temperatures.

Heat Advisory issued July 14 at 11:21AM PDT until July 15 at 9:00AM PDT by NWS Reno NV

* WHAT...High temperatures of 98-104 degrees expected in lower elevations through this afternoon with tonight's low temperatures in the 60s to near 70 degrees, resulting in widespread Major HeatRisk. * WHERE...In California, Lassen-Eastern Plumas-Eastern Sierra Counties and Surprise Valley California. In Nevada, Northern Washoe County and Greater Reno-Carson City-Minden Area. * WHEN...Until 9 AM PDT Tuesday. * IMPACTS...Heat related illnesses increase significantly during heat events, particularly for those working or participating in outdoor activities. * ADDITIONAL DETAILS...High temperatures on Tuesday will be about 5 degrees cooler compared to today, mainly in the mid-upper 90s for lower elevations, followed by more cooling Tuesday night, so the duration of this Heat Advisory has been reduced.

Extreme Heat Warning issued July 14 at 10:50AM PDT until July 14 at 9:00PM PDT by NWS Las Vegas NV

* WHAT...In Las Vegas and Moapa, highs between 110 and 115. In Death Valley, highs between 120 and 125. In Amargosa Valley, Pahrump, and Indian Springs, highs between 105 and 115. In the Colorado River Valley, highs between 110 and 120. * WHERE...Lake Mead National Recreation Area, Death Valley National Park, Northeast Clark County, Western Clark and Southern Nye County, Las Vegas Valley, and Southern Clark County. * WHEN...Until 9 PM PDT /9 PM MST/ this evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat events.

Heat Advisory issued July 14 at 10:33AM PDT until July 14 at 11:00PM PDT by NWS Eureka CA

* WHAT...Moderate heat risk is expected with highs from 100 to 105. * WHERE...Northwestern Mendocino Interior and Southeastern Mendocino Interior. * WHEN...Until 11 PM PDT this evening. * IMPACTS...Hot temperatures may cause heat illnesses. * ADDITIONAL DETAILS...Overnight lows around 60 will provide some relief in the valleys, but higher terrain may see lows remain in the 70s.

Extreme Heat Warning issued July 14 at 10:33AM PDT until July 14 at 11:00PM PDT by NWS Eureka CA

* WHAT...Dangerously hot conditions with high temperatures of 102 to 110. * WHERE...Trinity County. * WHEN...Until 11 PM PDT this evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat events. * ADDITIONAL DETAILS...Overnight lows around 60 will provide some relief in the valleys, but higher terrain may see lows remain in the 70s.

Heat Advisory issued July 14 at 10:33AM PDT until July 14 at 11:00PM PDT by NWS Eureka CA

* WHAT...Moderate to locally major heat heat risk is expected with highs between 100 and 105 in the valleys. * WHERE...Lake County, and Northeastern Mendocino Interior. * WHEN...Until 11 PM PDT this evening. * IMPACTS...Hot temperatures may cause heat illnesses. * ADDITIONAL DETAILS...Overnight lows in the low 60s will provide some relief in the valleys, but higher terrain may see lows remain in the 70s.

Heat Advisory issued July 14 at 10:33AM PDT until July 14 at 11:00PM PDT by NWS Eureka CA

* WHAT...Moderate to major heat risk is possible with highs of 96 to 102. * WHERE...Southern Humboldt Interior. * WHEN...Until 11 PM PDT this evening. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses.

Extreme Heat Warning issued July 14 at 10:33AM PDT until July 14 at 11:00PM PDT by NWS Eureka CA

* WHAT...Dangerously hot conditions with high temperatures of 102 to 110. * WHERE...Del Norte Interior and Northern Humboldt Interior. * WHEN...Until 11 PM PDT this evening. * IMPACTS...Heat related illnesses increase significantly during extreme heat events. * ADDITIONAL DETAILS...Overnight lows around 60 will provide some relief in the valleys, but higher terrain may see lows remain in the 70s.

Heat Advisory issued July 14 at 6:36AM PDT until July 15 at 11:00PM PDT by NWS Hanford CA

* WHAT...High temperatures up to 105 degrees expected. * WHERE...San Joaquin Valley, Coastal Ranges, Sierra Nevada foothills, Kern River Valley, and Yosemite Valley. * WHEN...Until 11 PM PDT Tuesday. * IMPACTS...Hot temperatures may cause heat illnesses.