Friday is "National Don't Fry Day", and since this weekend marks the unofficial start of summer, here's a good reminder to protect yourself from the sun.

Cancer organizations across America are teaming up to alert you about the dangers of extreme heat and exposure to UV rays. One of their biggest messages: if you think a sunburn you get today won't mean anything tomorrow...think again.

According to Dr. Katrina Smith, "With each sunburn you're more likely to develop chronic signs of sun exposure. This will be freckling, wrinkling, fine lines, changing in the texture. This can accumulate over one's lifetime and certainly increase your risk for skin cancer."

Another big mis-conception is that SPF can be layered to give you more protection, but that's not the case at all. "You certainly will not have more than what you've used at the highest SPF. So if you have an SPF 15 and you apply another SPF 15, you still only have an SPF 15" says Smith.

If you're out and about in the sun this weekend, here are a few quick tips:

-Drink two to three liters of water.
-Wear sun-screen, a hat and loose clothing.
-If you're feeling disoriented or sleepy, get yourself inside and into the air conditioning right away.