Help with Wedding Guest Outfit

Hi! I wasn't sure exactly which reddit to post to, but hope this works haha.

I've never been to a wedding before and they didn't give me a dress code or anything. I'm assuming its formal. It is set in San Diego, CA in April. The wedding takes place in a church and the reception at night is near the beach (which receives a lot of cold wind).

As someone who is always cold no matter the temperature, I rarely wear dresses. I want to wear a dress this time but I don't know how to style or layer them.

(For example, in the summer I put on a jean jacket over my t-shirt and am still cold. So I worry that I'll need something heavier than just a simple layer like a shawl/cardigan over my arms at the beach.) I don't want to look stupid showing up in a heavy coat LOL.

Do any of you have any ideas? Or ideas on how to layer for that? Or have any inspo pics I can try to follow?

Other things about me: I am a True Autumn, spoon body type, and 5'3".

Much appreciated!