Usually, I switch to drinking iced coffee (versus hot coffee, unless I'm in a very nicely a/c'd place) in late May or early June. In Los Angeles, I never actually switched off of hot coffee in the morning -- it was never all that hot. Here in central Texas, though, when the a/c runs all night to keep the house at 80' -- thats iced coffee time.
Alas, my heat production is such that I officially switched today (not that there won't be the odd hot coffee day after today). Once the upper 70s are hit, I start melting. This, from the gal who survived 100'F plus with 100% humidity for 3 summers in southwest China! With no a/c! Pregnancy has made me a wuss.
Its still cooling off at night, so even today the windows were opened this morning and the breeze through the house is nice. We get some fairly nice weather in the shoulder seasons here (Mar to mid-April and mis-Sept through Nov) and they are long enough to be really enjoyed. Here's to hoping Baby doesn't have too many allergies and window opening can continue!