I get the hot-weather-swelling too. Have done for years.
And I too find that sitting is the worst thing for it.
We don't have air con at work, so it gets hot and stuffy in the office. However, often that heat is year-round!
From the various things I have done to try and sort it, I have learned the following:
- my ankles swell a little in warm weather and a lot in hot weather
- my left ankle always swells worse than the right
- regular walking, moving around and stairs keep the swelling down. most of the time.
- sitting with my feet up (evenings) or lying in bed makes it go away (it is always gone by morning)
- the more I drink (and pee) the less they swell
- a mild diruetic that I took for a while for PCOS eliminates the problem completely - but I avoid all unnecessary drugs, so don't take it any more, since it wasn't working for the prescribed purpose
So now, when the temperature climbs, I drink twice as much pure, cold water.
this means I have to get up to pee VERY regularly
I use the office toilet at the far end of the building
I walk to and from work (pity to waste the good hot weather, eh?)
and now my legs only swell if I am stuck in meetings, or unable to move around.
I have also learned that 'avoiding salt' that mantra people use to prevent water retention... well it is not a good idea for my body.
If I don't have salt, potassium and magnesium, esp in hot weather, I get night time cramps, feel lethargic, heavy limbed and generally awful. So I eat more of them in hot weather. Works like a charm.