In some ways, day-trips have the potential of being more dangerous, and far more uncomfortable, than multi-day outings. Since we only plan to be out for a few hours, we often carry very little with us on day-trips. Some paddlers take little else than what they're wearing–a potentially serious problem should conditions deteriorate. If your return home is delayed by unfavorable conditions, like powerful winds, a lightning storm, sickness or injury, an unprepared paddler can become stranded without adequate shelter or protection from the elements.
That can lead to poor decision making: Without the gear to wait out bad weather, paddlers are likely to feel that the only option is to paddle home, regardless of conditions. The solution is to always carry a few key pieces of gear, food and water that will enable you to safely spend a night out. We're not going to load up our kayaks with expedition gear for every paddle trip, so the idea is to develop a survival kit that is small and light enough to bring every time. Total comfort may not be possible, but simple, adequate food and shelter fits in one medium-sized drybag.
— Alex Matthews
PACK SHELTER. Try a lightweight tarp large enough to provide shelter from gusting wind and torrential rain, or spend a little more for a modern lightweight bivy system that packs down to the size of your hand. Include cord and pegs for maximum versatility in tarp setup and to secure it in bad weather (it always helps to have extra cord for a bivy too).
SLEEP WARM. A lightweight sleeping bag is Job One. A 32-degree synthetic bag may not be the warmest, but it will work in a pinch and stuffs down small. The best way to stay warm is by climbing in a sleeping bag.
SLEEP COMFY. A Therm-a-Rest or foam pad is worth the weight. Not only comfortable, a pad insulates you from the cold ground keeping much-needed heat close to your body.
THE HEADLAMP PLAYS DOUBLE DUTY. You'll be able to see where you're going, making sure you bed down above the high tide (or water) line, and also acts as a signal lamp in case rescuers need to find you.
CARRY EXTRA ENERGY. A good emergency food kit includes a liter of water, a multi-tool, fire starter, and high-energy non-perishable foods such as trailmix, Powerbars and Chunky Soup or other canned goodness. You should be able to stow the above items in one drybag that goes with you on every paddling trip.