How do you know if the brown spots in your lawn are caused by the heat (that you can’t do anything about) or something else (that you can do something about)?
Are the brown grass blades mixed in with the green grass blades in no particular pattern almost like the lawn is dry, yet you have been getting rainfall? This could be an insect problem or your lawn could be starving if it has been more than a few months since the last feeding. One clue to look for with insects is the presence of lawn moths when you mow. The moths do not damage your lawn, however they lay eggs for sod webworm, cutworm and other lawn damaging insects. Chinchbug damage also looks like the grass in this photo. Solution: Feed and protect your lawn with an application of Turf Builder with SummerGuard. Be sure to water after spreading. If your lawn does not need feeding, apply Ortho Bug B Gon MAX.
Are the brown spots following a particular pattern such as a circle? Within the circle the problem may start with some of the grass blades turning brown with spots on them. There are a range of lawn fungus problems like dollar spot, brown patch, red thread and summer patch that show up as circular patches in your lawn. These problems can crop up when you are getting higher temps during day and night and more rain and humidity. Solution: Treat your lawn with Scotts Lawn Fungus Control.
Do some areas of your lawn always seem to turn brown first? Probe the brown spot with a screwdriver and compare this with the healthy lawn areas. I have found that the typical brown, tan-colored “dry spot” can show up because of a pocket of poor soil, a buried rock that is just below the soil surface, or an area where lawn sprinklers don’t provide complete coverage making it tougher for the screwdriver to penetrate. So you think your lawn is getting adequate water, however this dry spot is the first area to go brown. Solution: Give extra water to this area until you are able to improve the soil in this spot, dig up buried rock or adjust sprinklers.