Numerous articles give you info about how to layer, stay away from cotton, wool is your friend etc etc. If you need help deciding how to dress, please seek one of those articles out. It will be different for every region so I won't attempt to make a generalized list here.
What I do want to bring to the forefront is universal however. If you get swamped, submerged or turtle into the water, how long do you have before death can occur?
The PFD Manufacturers Association compiled all of the data and shared some scary numbers.
"Cold water (less than 70° F) can lower your body temperature, causing hypothermia. If your body temperature drops too low, you may pass out and then drown. The human body cools 25 times faster in cold water than it does in air."
Water that is just above freezing temps (32.5F) has a survival time of less than 15 minutes.
Water up to 40F slightly increases that time to 30 minutes.
Water from 40-60F (where most of our waters are now) can cause death in 1 hour.
Water from 60-70F has a 2 hour time window.
Above 70F is typically survivable from the temperature though exhaustion can set in and cause drowning.
What this assumes is that you stay in the water. If you get soaked, then back up on your kayak and the wind is blowing, the water in your clothes will not stay at that temp. It'll drop like a rock.
The best plans are to carry a change of clothes, have a buddy near by and if you do turtle, get your butt back to the car. Once there, strip down, towel off, put on the dry clothes and blast the heater.
Don't be a statistic by being stubborn. If you get soaked, get out.