First and foremost, bugs!
Mosquitoes are out already in many parts of the country, especially in damp areas and places with standing water. The west Nile virus is spread by infected mosquitoes and can cause serious illness, even death in extreme cases.
This is also prime season for bee stings and tick bites. Ticks can carry Lyme disease and rocky mountain spotted fever. Bug repellent with deet can help ward off the pests, though doctors say to be careful when spraying it around food and children.
Poison ivy and oak plants are also popping up. Just brushing by the toxic plants can cause a nasty, itchy rash that often needs steroids, oatmeal baths or antihistamines for relief. You can't "catch" it from another person's skin, but oil from the plant can spread into the fur of your pets and can stay on unwashed clothing for a long time.
Experts with the national park service say washing the affected area with soap and cold water as soon as possible can help lessen the severity of the rash and keep it from spreading.
Don't forget the sunscreen!
Of course there's the most common summer malady, sunburn. Protecting yourself from the sun is extremely important and a bad burn can put you at risk for melanoma, a sometimes deadly form of skin cancer. The American cancer society suggests using a sunscreen with an SPF of at least 15 and apply it every two hours. Also try to stay indoors from 10 am to 4 pm, when the sun is strongest.
If you do get burned, cold compresses, ibuprofen and soothing lotions can help.