Which months would be best for tuning a piano? In the winter, I know I'll turn up the heat, thus drying the air(only a few pianos in this world are worth freezing for and I know my eighty-five year old piano is not one of them), and I know during the summer, humdity rises. Should I wait for the more stable spring and fall months?

Living in the San Francisco Bay Area, does this even matter at all?

thanks for your help!
kasa

When it needs it. Here in Oakland, it really does not matter. Or more exactly, individual circumstances, such as whether your house is extraordinarily damp, or if there is a bay view, matter more.

Pianos go out of tune in large degree due to environmental changes, some instruments more than others. I suggest getting it tuned a month after such a shift has taken place, to give the piano time to react and stabilize somewhat. So, a month after you turn the heat on in the fall and a month after the heat goes off in the spring would give you the best results.
You may also consider a piano humidifier/dryer system to mitigate the seasonal swings.

In your area, regular tuning should probably do it, though.