The problem is that we are having an exceptionally hot and dry summer here, so I wonder if aerating will cause it to dry out more? Or could it possibly help the grass get more water, since in some places, the grown seems so compacted the water runs off?

I have a predominantly bermuda grass lawn, and I water it every other day.

BTW. Be careful about watering every other day. Since it's warm season grass it doesn't matter as much as if it were a cool season grass, but when you water deeper and less frequently (maybe more like every 4 or more days) it encourages the root system to go down deeper in search of water - creating a stronger root system. The aeration will help with the deeper watering by not allowing as much runoff.

If you were to adjust your watering schedule do it slowly do it slowly by bumping it up 1 day at a time over a certain amount of time.

Your soil is hard, but not compacted. Furthermore your soil is hydrophobic (immediate water runoff). Soil can be very fluffy and still be hydrophobic.

How long do you water when you water? I'm guessing 20 minutes and the runoff is a problem. One of the big problems we see here in the forums is water frequency. According to the consolidated wisdom of the ages here, you should be watering more like once a week and watering a full inch. How long it takes your sprinkler to put down an inch can be determined with tuna cans placed around the yard. If it takes an hour to apply 1 inch, then that's how long you need to water. However, don't ever let the water run off. If you start to get runoff, stop immediately and let the water soak in. Then continue stopping as needed until you get a full inch down.

With that practical experience behind us, one way to get the water to sink in instead of running off is to prespray before you irrigate with baby shampoo. Baby shampoo will help the irrigation water to soak into the soil. Repeat the shampoo every other week for 2 months and your soil should soften up runoff stop. This usually works well enough that you won't think about using the aerator.

I use the Ortho hose end sprayer to apply soap. The general rate is to apply 3 ounces per 1,000 square feet. If you have 2,000 square feet, then put 6 ounces of soap into the sprayer and fill it with water. It doesn't matter what you set the dial on, just apply until you run out. Try to keep it even.