I'm doing Nation's for the first time this year. For those who are also doing Nation's, I was wondering whether you plan to use a wetsuit? (assuming the race is wetsuit legal)
If the race is wetsuit legal for awards, then yes, I plan on wearing a wetsuit.
I think the honest answer is it comes down to personal preference and more importantly how easily you overheat.
My personal preference is to wear a long sleeve all the way up to the legal cut off at 78 degrees. Others prefer a sleeveless at hotter temps, and of course others a speed suit.
You may want to get out to the WaveOne happy hour swims at National Harbor tonight or next week to help you better make that decision. The Potomac water temps have been floating just above or at the limit of above 78 for the last week.
I'm guessing that USAT is potentially looking to drop the legal temperature based on a study that they are currently conducting. I actually thought they already had dropped it to 76, in line with WTC, but apparently not. Looks like the current temperate at 78 is potentially too high being that it was set based on "scientific, peer-reviewed research performed in 1994."