The weather in Yosemite National
Park during the summer is
very predictable. From the middle of June until late September it rarely
rains except for a rare, wandering afternoon thunderstorm that can produce lightening and
moderate rain for a while at the higher elevations. This happens mostly at
Tuolumne Meadows and less so in the valley. On balance, this may happen about once or twice a month (yes,
that's a month) at most. The humidity is very low as it is all over the San
Joaquin Valley. High temperatures range from low 90's (remember, low humidity) to
high 70's. Average is about 75 to 90. Lows can get rather chilly. The
valley is at the 4,000 ft. elevation, and can get quite cold at night, about 45
to 50 degrees.
During the spring, there is no telling what
might happen. It can be rainy and cold one day, and then have cobalt-blue skies and
80 degrees the next.
Winter is the exact opposite. Storms
come from out of nowhere, and it can rain and blow for a few days. Yes, Yosemite is
beautiful in winter, but be prepared. DO NOT go far into the backcountry after
October 1st. Two miles in should be your limit; you need to be able to
get out of the wilderness quickly in case of an early winter storm.