A freeze watch is in effect for tomorrow night in Pleasanton and the Tri-Valley tonight where the temperature today is expected to reach only 52 degrees. Variable winds at 10 to 20 mph are expected.
A temperature of only 27 degrees early this morning tied a record low at the Livermore Municipal Airport set in 1969. Frost was seen throughout the Tri-Valley early this morning with car windshields in Pleasanton covered with ice by 7 a.m. with a temperature of 29 degrees.
Tonight the low temperature is forecast for a more mild 36 degrees with as much as a quarter-inch of rain expected.
For Monday, rain will continue with a half-inch expected and a high mid-day temperature of only 42 degrees.
The National Weather Service's freeze watch is due to a cold air mass that is traveling down from Canada and will be moving into the Bay Area by Monday night. The watch is in effect from late Monday through Tuesday morning.
Most areas will experience temperatures in the mid-to-upper 20s for several hours, according to the weather service. These conditions could kill crops and other vegetation.
The Weather Service says plants should be covered to keep them from dying.