Extreme heat is defined as summertime temperatures that are much hotter and/or humid than average. Protect yourself and others when it’s hot outside by staying cool, staying hydrated and staying informed. Learn more about extreme heat and other health advisories. UV index safety and resources Do not burn or tan: Avoid intentional tanning. Seek shade: Get under cover when sun’s rays are strongest between 10 a.m. and 4 p.m. Wear protecting clothing: Long-sleeved shirts and pants, wide-brimmed hat and UV-blocking sunglasses. Generously apply sunscreen: Use a broad spectrum sunscreen with a sun protection factor (SPF) of 30 or higher. Apply sunscreen generously. Apply 15 minutes before going outdoors and reapply every two hours or after swimming, sweating or toweling off. Check the UV index every day: The higher the UV index, the more you should do to protect yourself from the sun. When planning outdoor activities, follow EPA’s safety recommendations. Protect those at risk from UV rays: Children, the elderly and those with special needs may be more sensitive to the sun. Babies younger than six months should be protected from the sun using hats and protective clothing.