in august the weather is bound to be over 100 degrees in some places.
this is the best time to visit the shasta cavernns where the temp stays at 50 degrees (F). the caverns are on I-5 north of Redding. there is a boat trip across shasta lake and a bus trip up the hill to get to the entrance. there are also other caverns near the Gold Country--Mother Lode area along hiway 49 south of I-80. Mercer, Moaning and other caves are near the Calaveras Big Trees state park. Redwoods grow by the coast and in the high sierras--two varieties of them..Sempervirens, and giganteum.

yosemite national park is quite a jewel, visited by millions of people each year. the granite domes are awesome! August is also the time for
the ;strawberry music fest....labor day...end of aug. which is one of the best music festivals of all....

i can offer more info--hot springs, etc. Laurel