I actually have a gym membership, but I have not been there in 6 months. I do home workouts manily because I read the police reports and there have been lots of car windows shattered in the gym parking lot and even locks cut off in the locker room to steal purses.
I also live in hot location (south Texas) and we are in the triple digits now. I get up at 6:30 and jog 2 or 3 miles, then I swim laps (I live in a senior citizen apartment complex). If I don't work out in the morning, I try to ride my bike 7-8 miles at dusk.
If you have a dvd player you could invest in couple of exercise dvd's. I have the Leslie Samsone walking dvd.
Or if you want an exercise bike or stepper try looking at a thrift shop or garage sale. I got a bike for 20 dollars and a readmill for 50 that way.
On the other hand, if you would go to gym and take the classes they can be very motivating and fun (yoga, pilates, zumba, water exercise). And if the gym has steam room, saura, and hot tub those are great rewards after a workout!
Good luck on your decision.