I started collecting formal data on my swims in 2020 because the majority of it was done outside. I plan to continue to collect more for fun. :)
Most of my pool swims average 2km. Open water swims vary by water temperature, anywhere from 0.5 to 10 km. With pool closures in 2020, it was enough to just get in the water, so I focused swimming at all rather than distance.
Swim practices are usually an hour long. Long distance swims are about 3km/hr. As the water temperature drops, swims get shorter.
In years with more pool swims, the average is higher because pools are kept around 28C (ish). More lake and sound swims pull the average colder.
This data is only semi-accurate, as I record total swim time and don't bother to stop it when I take breaks.
This data tends to be all over the map when the pool and open water swims are interspersed. Since 2020 I haven't swum in a pool, so the chart is actually a pretty accurate representation of the temperature of Lake Washington (with some Puget Sound tossed in there).
Pool temperatures are on the too-high-to-workout range, typically 28c. The lake gets into the mid-20s in the summer and as low as 8c around February. Because it's a larger body of water, the Sound neither gets as cold nor as warm as the lake, so swimming in the Sound in the winter is warmer.
I try to go all year round, but I do tend to wimp out when the water is at its coldest in February/March.
If I'm in a pool, I swim in a swim suit, but swimming in the lake and the sound gives me different options. I swim using a wetsuit if I am short on time because recovery from cold exposure takes a while. I can't drive until I stop shivering. I am working towards increasing my cold tolerance, however, so weekend swims I forego the wetsuit and test my fortitude. I have also swum a few times with nothing on at all.
My swim partners vary throughout the year, with the team mostly being pool swims, and then individual friends when we can be coordinated. If I want to do a quick swim at the drop of a hat, I go by myself.
Until the pandemic started and the local pool closed, I had been swimming almost exclusively in chlorinated water. Since then, however, it's been the lakes and the Sound. For most of the year I swam in Lake Washington. As it gets colder, the Sound maintains a higher average temperature because it's a larger body of water, so I've migrated to it rather than the colder lake water.