I wear rubber boots all the time. We've been getting close to 90 recently but it hasn't had an effect on the comfort level yet- I'm sure 115 will be a different story!
The only problem I had with the rubber boots was the "break-in" period. They were really really tight on the outside of the big toes. The first night I wore them at a job I had to run across the street to a gas station and buy bandaids to put on the blisters! Luckily they did break in and are very comfortable now.
I think they were about $15.00 at Walmart.
JK