If the weathermen knew for sure, they'd all be rich. Take the warmest, driest gear
you have. Diving
goggles might be useful in wind-driven rain. If you have the gear
, but don't need it, fine. If you need the gear but don't have it, not fine. We went transatlantic in June and despite multiple layers of clothing
, hats, socks & gloves, were cold for at least a week, even with a heater
on board trying to warm us up. You are further south, but night watches can be cold even in summer.