Warm temperatures and a weak low pressure center off the southern California coast will set us up for sunny mornings with a slight chance of afternoon showers and thunderstorms for the next several days. High temperatures in the valleys will hover near the 80 mark throughout the weekend, and really won’t cool off much until the middle of next week when we drop a cool low down out of the north.

Average_Annual_High_Temperature_of_the_United_States

Here’s a question that I get a lot: “How are average temperatures computed? Is a daily high temperature the last 20 years of daily high readings on the date, or is the average reset once a year or some other period?”

Locally, the NWS uses a 30 year rolling average, updated every year. For the numbers that go into the national climate database, they still use a 30 year rolling average, but they only update it at the end of every decade. The last time they updated the averages was in 2010, and they won’t update again for another five years. So in essence we are really operating with 35 year old data.

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