Excessive Heat Watch from Friday afternoon through Sunday evening for Carquinez Strait and Delta-Central Sacramento Valley- Clear Lake/Southern Lake County-Motherlode-Mountains Southwestern Shasta County to Northern Lake County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Northern San Joaquin Valley-Shasta Lake Area / Northern Shasta County- Southern Sacramento Valley-West Slope Northern Sierra Nevada- Western Plumas County/Lassen Park.
Clear skies across the region early this morning. Current temperatures are considerably warmer compared to 24 hours ago and generally range from the 30s to lower 40s in the mountain valleys to the 50s to mid 60s elsewhere.
Ridge builds into the end of the week, though weak systems passing to the north may bring occasional high clouds at times. Highs in the Central Valley will warm to the beginning Friday.
Extended discussion (Sunday through Wednesday)
Strong high pressure ridge over the west coast will bring fair skies and well above normal temperatures through the extended period. Much of the CWA below around 5000 feet expecting temperatures in the heat advisory criteria range.
Daytime highs throughout the Central Valley are currently expected to range between 103 and 107 degrees.
Overall airmass remains fairly constant through the remainder of the extended period as upper ridge axis remains over the western U.S. Therefore, not expecting much change in daytime highs or overnight lows through the extended period.
About only area that might see a little cooling would be the Delta where an increased delta breeze will bring a slight cooling next Monday and Tuesday.
Latest models hinting at southerly flow aloft bringing some moisture up the Sierra for a slight threat of afternoon showers or thunderstorms there south of about Tahoe and have added slight threat there to current forecast package.