You're not going to like this, but your air-conditioner is actually making it harder for your body to handle the heat outside. If you want to feel more comfortable outdoors during the hot summer months, you need to cut back on your AC use.
If you can't beat it, join it. If you want to be more comfortable in the heat, Scientist Stan Cox, author of Losing Our Cool, suggests you have to become one with the heat. According to the adaptive comfort model, your ideal comfort temperature is based on whatever temperature you were recently exposed to. If you're always indoors with the AC blasting, going outside can feel like walking into a furnace. On a psychological level, your body makes the air feel hotter. Cox explains: "If we experience more warmth, we can tolerate more warmth."
It's like getting out of a cold pool to climb into a warm hot tub: it's going to feel a lot hotter than if the pool was heated. So if you want to make the most of the summer and feel less miserable when you head outside, you need to ditch the AC and let your body get used to the heat. Lower or turn off your AC at home and drive around with the windows down. You won't be very comfortable at first, but you'll get used to it after a while -- and you'll save some money in the process too.