Actually Summer doesn't start until about the 21 of June, but it is a lot cooler this year in Northern CA. It has been about 72 in the day time, sometimes hitting 80, but usually we would be having about 85 to 95 weather about now. It has rained several times over the last few weeks also. while this is not unheard of it has been quite a while since it rained this late in June and the temps at night are dropping down into the 50s. I am only at about 1000 foot elevation also, that means a large part of Northern CA is much cooler.
What part of NorCal are you in? I’m here in Vallejo...