Def don't need chains this time of year. Alta peak trail can be the best rewarding hike if the weather is right. It's not a beginners hike. I don't wanna spoil it but some breathtaking views of some beautiful landscapes
I would look up the weather for the three rivers area but you should be OK. Sequoia is relatively low down, the roads are good and well and quickly plowed. You may be required to carry chains even if you don't need to use them. I've been there even earlier in the year and while there was snow the roads were all clear.
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