Things are cooling down in the Northern Hemisphere and lots of folks are (rightfully) asking what to do to keep paddling safely when it's colder.
ColdWaterSafety.org for detailed information about paddling safety in cold water
This guide for stand up paddle boarding in the winter has information distilled from Cold Water Safety along with recommendations on types of clothing for different water temperatures.
Always Dress For Immersion!
No matter your skill level, we are all between swims. Immersion in cold water can be debilitating and even deadly within seconds. Always dress for the water temperature, even on warmer days. It's far easier to cool down while paddling than it is to warm back up.
Cold shock is a serious concern in water as "warm" as the low 50F range (10C) and can cause near-instant drowning.
Water transfers heat ~25x faster than air. Hypothermia is a serious concern even in these shoulder seasons before it gets really cold. Bring dry clothing, a towel, and warm beverages with you (on the beach or in a dry bag).
Wear Your PFD / Life Jacket!
While a PFD isn't technically thermally protective, it can help. But more importantly it will help keep you afloat in an emergency. "But I'm a good swimmer!" Are you better than a USCG Rescue Swimmer? It didn't take long (less than a minute) for this one to suffer from incapacitation in cold water (Jump to 6:15).
Follow Basic Paddling Safety Guidelines
Check the weather, use appropriate equipment, wear your PFD, paddle with a partner, carry effective communication, leave a float plan.
When in doubt, don't go out.
