Applying lots of moisturiser and skin care products can help, I think, though it might get uncomfortable with the sweats. I think the best option is to drink enough water, eat more fruits and vegetables, and try to avoid going out in the sun.
Moisturise before and after swimming.
Also keep out of the sun when you can. I find that my skin dries out more when the heat is dry whereas in humid places like Darwin, it does not dry out anywhere near as much.
Drink lots of water.
Using a toner after cleansing is extremely important as it preps your skin to absorb your moisturiser more effectively.
Always use sunscreen after your day moisturiser, which you should also touch up around mid-day as its effects wear off over the hours and over the extent of exposure.
In fact, whether summer or winter, you should still moisturise and apply sunscreen to protect against skin damage.