Before it gets to hot you want to service your AC/Heating unit. You do not want to get a break down during the hottest time of the year. Getting it serviced early will prevent costly repairs. Make sure to replace air filters when needed and check for any leaks in the ducts.
One of the most overlooked appliances in the home is the dryer. Make sure you clean out filters and make sure there is no debris in the duct. Other appliances to check will be the washing machine, refrigerator, dishwasher, and so on. Make sure everything is kept clean and replace any parts if needed.
Before the heavy rain hits you will want to clean out all the gutters. If you neglect the gutters the leaves and dirt will make cleaning very difficult. There are specialty tools and chemicals that make this task easier. If you do not have a screen on the gutters this will be something to consider as it keeps large particles such as leaves out.
Another item that will need inspection is the exterior of the home. The exterior will take a beating from the elements and maintenance will be required sooner or later. Pressure wash the exterior of the house along with any outdoor furniture. Fix and paint anything that requires a touch up. Fix repair and paint outdoor furniture such as chairs, benches, and picnic tables. If you have not yet build yourself a picnic table go here for picnic table instructions.
Before the weather gets to hot you will want to get any planting out of the way. If you need more shade in a certain area consider planting some trees. Trees will provide a cool area to relax during the hot summer season.