In the mountains of the North State, Tuesday turned into another hot one.  In the Sacramento Valley, it cooled down!

That's because the delta breeze really kicked up Tuesday.  The Coast Range makes a very effective wall to the cool Pacific Ocean for us in the North State.  The only low elevation 'pass' through the mountains is the Carquinez Straight, near the Bay Area.  So when there is a strong onshore breeze, it has to go through the Straight first, then the Sacramento River Delta, then into the rest of the Sacramento Valley... hence the name, 'delta breeze'.  That delta breeze is really modified marine air, which is when it kicks in, Valley temperatures cool down.  And since it travels from the Bay Area northward, the biggest influence is closest to the delta.  It takes most of the day to finally make it to Tehama and Shasta counties, which is why Red Bluff and Redding didn't cool down too much Tuesday... but areas further south saw a big cool down!  And the delta breeze rarely effects the mountains, which is why Weaverville was hotter than Chico Tuesday.

Expect that delta breeze to continue to blow the rest of the week, like it did on Tuesday.  So expect similar temperatures the rest of the week.  By the weekend, high pressure finally slides eastward, allowing everyone's temperatures to start to cool down.  By next week, Valley highs dip into the 80's.

So cooler temperatures are on the way.  The cooldown started Tuesday in areas affected by the delta breeze.

Kris