I was in Palo Alto--down the road from San Mateo--on September 6. That afternoon, it was pretty hot, and you might have benefited from air conditioning.
I think it might have hit close to 80 at home on the 6th. I recall taking a nap with a fan on and waking up needing a blanket about 10pm or so. I was in Arizona the two weeks previous so I had became used to cowering indoors with the AC on...There were at least 3-4 days this month where we thought it too hot to cook dinner so we fired up the barbeque or went out to eat.