@Barbara Racz You might be wise to ask for advice from a quality outdoors store. Usually under a breathable shell you would have one or two warm layers. Something like a fleece and a warm vest might be adequate.
The ball cap being worn was not adequate during sunny days on the first third of the walk from SJPDP.at the end of April. My son burned his left ear badly enough that it bled for a while. Sunscreen and or wide brimmed hat - tilted to the left.
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