Weather Alerts for California

Recent Locations: Del Valle, TX Vernon Center, NY Cupertino, CA

Current Alerts for Cupertino, CA: Heat Advisory

1. Extreme Heat Warning for: Apple and Lucerne Valleys

2. Extreme Heat Warning for: Coachella Valley; San Diego County Deserts; San Gorgonio Pass Near Banning

3. Extreme Heat Warning for: Cuyama Valley; Santa Clarita Valley; Santa Lucia Mountains; Southern Salinas Valley; San Luis Obispo County Interior Valleys; San Luis Obispo County Mountains; Santa Ynez Valley; Santa Barbara County Interior Mountains; Western Santa Monica Mountains Recreational Area; Calabasas and Agoura Hills; Western San Fernando Valley; Eastern San Fernando Valley; Southeastern Ventura County Valleys; Santa Susana Mountains; Southern Ventura County Mountains; Northern Ventura County Mountains; Interstate 5 Corridor; Western San Gabriel Mountains and Highway 14 Corridor; Eastern San Gabriel Mountains; Western Antelope Valley Foothills; Eastern Antelope Valley Foothills; Antelope Valley; Los Angeles County San Gabriel Valley

4. Extreme Heat Warning for: Indian Wells Valley; Mojave Desert Slopes; Mojave Desert

5. Extreme Heat Warning for: Santa Ynez Mountains Western Range; Santa Ynez Mountains Eastern Range; Los Angeles County Inland Coast including Downtown Los Angeles; Eastern Santa Monica Mountains Recreational Area

6. Extreme Heat Warning for: West Side Mountains north of 198; Coalinga - Avenal; Fresno-Clovis; West Side Mountains South of 198; Buena Vista; Bakersfield; South End San Joaquin Valley; Mariposa Madera Foothills; Fresno-Tulare Foothills; South End Sierra Foothills

7. Extreme Heat Warning for: Western Siskiyou County; Central Siskiyou County

8. Heat Advisory for: Lassen-Eastern Plumas-Eastern Sierra Counties

9. Heat Advisory for: Los Banos - Dos Palos; Merced - Madera - Mendota; Planada - Le Grand - Snelling; West Side of Fresno and Kings Counties; Caruthers - San Joaquin - Selma; Buttonwillow - Lost Hills - I5; Delano-Wasco-Shafter; Hanford - Corcoran - Lemoore; Visalia - Porterville - Reedley; Southeast San Joaquin Valley; Kern River Valley

10. Heat Advisory for: North Bay Interior Mountains; East Bay Interior Valleys; Santa Cruz Mountains; Santa Clara Valley Including San Jose; Eastern Santa Clara Hills; East Bay Hills

11. Heat Advisory for: North Bay Interior Valleys; San Francisco Bay Shoreline

12. Heat Advisory for: Northeast Siskiyou and Northwest Modoc Counties; Modoc County; South Central Oregon Cascades; Klamath Basin; Northern and Eastern Klamath County and Western Lake County; Central and Eastern Lake County

13. Heat Advisory for: Northern Humboldt Interior; Southern Humboldt Interior; Northwestern Mendocino Interior; Southeastern Mendocino Interior

14. Heat Advisory for: Northern Trinity; Southern Trinity; Northeastern Mendocino Interior; Northern Lake County; Southern Lake County

15. Heat Advisory for: San Bernardino and Riverside County Valleys-The Inland Empire

16. Heat Advisory for: San Bernardino County Mountains; Riverside County Mountains; San Diego County Mountains

17. Heat Advisory for: San Diego County Inland Valleys

18. Heat Advisory for: San Luis Obispo County Inland Central Coast; Santa Barbara County Inland Central Coast; Lake Casitas; Ojai Valley; Central Ventura County Valleys; Palos Verdes Hills

19. Heat Advisory for: Santa Ana Mountains and Foothills; Orange County Inland

20. Heat Advisory for: Shasta Lake Area / Northern Shasta County; Northern Sacramento Valley; Central Sacramento Valley; Southern Sacramento Valley; Carquinez Strait and Delta; Northern San Joaquin Valley; Mountains Southwestern Shasta County to Western Colusa County

21. Heat Advisory for: Southern Salinas Valley/Arroyo Seco and Lake San Antonio; Santa Lucia Mountains and Los Padres National Forest; Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park

22. Red Flag Warning for: Cuyama Valley; San Luis Obispo County Mountains; Santa Ynez Mountains Western Range; Santa Ynez Mountains Eastern Range; Santa Barbara County Interior Mountains

23. Red Flag Warning for: Fort Tejon

24. Red Flag Warning for: Santa Clarita Valley; Santa Susana Mountains; Southern Ventura County Mountains; Northern Ventura County Mountains; Interstate 5 Corridor; Western San Gabriel Mountains and Highway 14 Corridor; Eastern San Gabriel Mountains; Western Antelope Valley Foothills; Eastern Antelope Valley Foothills

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Weather Topic: What is Rain?

Home - Education - Precipitation - Rain

Rain Next Topic: Shelf Clouds

Precipitation in the form of water droplets is called rain. Rain generally has a tendency to fall with less intensity over a greater period of time, and when rainfall is more severe it is usually less sustained.

Rain is the most common form of precipitation and happens with greater frequency depending on the season and regional influences. Cities have been shown to have an observable effect on rainfall, due to an effect called the urban heat island. Compared to upwind, monthly rainfall between twenty and forty miles downwind of cities is 30% greater.

Next Topic: Shelf Clouds

Weather Topic: What is Sleet?

Home - Education - Precipitation - Sleet

Sleet Next Topic: Snow

Sleet is a form of precipitation in which small ice pellets are the primary components. These ice pellets are smaller and more translucent than hailstones, and harder than graupel. Sleet is caused by specific atmospheric conditions and therefore typically doesn't last for extended periods of time.

The condition which leads to sleet formation requires a warmer body of air to be wedged in between two sub-freezing bodies of air. When snow falls through a warmer layer of air it melts, and as it falls through the next sub-freezing body of air it freezes again, forming ice pellets known as sleet. In some cases, water droplets don't have time to freeze before reaching the surface and the result is freezing rain.

Next Topic: Snow