Your outer wear is important to prevent windchill - where your clothing is wet and the wind further chills you down. You should be wearing a thermal base layer that stays warm when wet and dries quickly, but on windy and cold days you will need an outer layer that keeps the wind out and your body warmth in. Even on warm days we carry a paddling jacket (cag) in an accessible part of the kayak (day hatch or behind the seat) in case conditions change - you can still get cold in windy conditions on a warm day.
Dry pants are a great addition to your paddling kit on sea kayak trips where being wet all the time would be a real drag! South West Tassie wilderness was one such place - having dry feet and legs really enhanced the enjoyment of the scenery! Even though it was summer it was still coolant wet. Dry pants are also great when kayak fishing - they keep off the sun and keep you warm while waiting for that big one to bite!
What to look for in outerwear:
Keeping dry in the Tasmanian summer (SW Tassie Wilderness) in Kokatat Goretex TecTour Anoraks and Hydrus 3L Pants!