When I have several reasons, can I use conjunction "since" or "because" multiple times in one sentence?

e.g., I like spring. Reason 1: It's warm. Reason 2: I don't have hay fever.

a) Since it's warn and since I don't have hay fever, I like spring.
b) Since it's warn and I don't have hay fever, I like spring.

Which sentence is natural/correct, a) or b)?