Hi,
Here's a link which you might have for weather in the SJSP.
http://www.pstramway.com/cams-weather.asp
Presently it's 60 & 35 as you'd mentioned, it can get into the teens at night if weather moves in.
The wind is what can make it Cold, if it's calm & the suns out,I've snoeshoed in short sleeves in the 40's. as the sun is strong up there.
If the forest gets hit, (I've heard a mild El Nino prediction), you could have 2 ft. on the ground.
Have a great time, here's a link to SJSP:
http://www.parks.ca.gov/?page_id=636
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