Scientists should study brides. Why? Because they seem able to endure sub-freezing temperatures without popping a goosebump. I've seen it so many times. Perhaps it's adrenaline. The brides are able to stand uncovered for the length of the ceremony plus photographs. I recommend having a standby wrap, though. Here's a recent bride from England, totally unphased by the snow and low temperatures (in the low 20's F.) The lake in Central Park--frozen!
This British couple's wedding was delayed due to a snow storm that grounded flights from London. Lucky for my couple, my contracts contain an "acts of nature" clause. So, no extra fees, despite a rescheduled ceremony.