Originally Posted by rumrunn6

just read this

If you sweat more, will you have to pee less?

Actually, excessive sweating will make you need to urinate more.
Believe it or not, sweat is actually less concentrated in salt relative to the blood, so when you sweat you are actually losing more water than salt. This leads to an increase in salinity of the plasma volume, known as hypernatremia.
The body's normal response to hypernatremia is to increase salt excretion by the kidneys. However, one cannot just excrete excess salt, it has to be excreted with water. The kidneys will respond to the increased salt concentration by concentrating the urine as much as possible, but you will still need to pee in order to excrete the salt and in the end will likely end up urinating more.
The renal system is very intricate and highly convoluted (pun?) so this is a simplification, but hopefully it will suffice.

and ...

It's common. The heat led to the sweating which greatly increased what is called your insensible water/fluid loss. It is not a problem at all, unless you are not drinking enough to cover your increased fluid needs. And over an extended time, you'd need to get some electrolytes in.
In healhcare, with critically ill patients, insensible water loss is estimated with various tools, or via descriptors, such as: 103 temp, shaking chills, profuse sweating, soaked bedding ( top and undersheet) x3 in 8 hour shift. Then measured intake and output is given. In this situation, the urine output might look quite alot less than the amount normally expected, but would be judged to be appropriate due to the great increase in insensible water loss.
You see this all the time in distance runners, for instance. They are being rehydrated along the way, and yet no one is stopping for a potty break.
I live in the deep south and do lots of yard/plant work. With the weather we've been having (heat indexes of 111-120!) I am drenched in no time flat. Sometimes I may work for 3 hours with short rest periods , pouring sweat and drinking HUGE amounts of water to cool off. I don't pee most of that water out - I sweat it out and when I do urinate later, given good intake, my urine is not concentrated. I salt my food adequately and take in enough potassium, so that is never a worry.
Look up "insensible fluid (or water) loss" for more info.