Welcome to the forum Dee.
Never had any troubles with my 790 in the summer, it runs just fine!! Now the operator has nearly croaked a time or two in the 98 deg weather lol. To be more serious, I've never felt the hoses on mine after running it a while, but now you got me wondering and I will check it the next time I've had it running for a while.
Btw, in case you aren't aware, there's a simple little trick you can do to the 790's to increase the hydraulic pressure. The hydraulic relief valve is set to 2000psi at the factory, but it can be safely increased to 2500 psi and give you a little more lift capacity on the loader (if yours has one) and on the three pt lift too. I did it to mine, and it makes a difference. If you're interested, there are several threads on it and you can use the search function and you should be able to find some of them. Basically it involves adding some shims that you can get at your JD dealer for about $10 bucks.