The .60 update is based in summer, so you will get hot faster and cool down slower. My tip would be to use some online map to find one of the small ponds scattered all around the map and get in it to cool off. However, don't go in with your gear on - just take your stuff off and put it to the side.
Here is a map showing some of the streams/ponds in Cherno. It's an outdated map, but it will give you an idea of what I'm talking about.