There's a little bit of confusion about LEDs and temperature. The good news is that, unlike CFLs, LEDs generally do well in the cold. (Fluorescent bulbs may be dim or flicker or not come on at all in cold temperatures.) Case in point: many car headlights are now LEDs.
On the warm side of things, you may have heard that LEDs are heat sensitive. This didn't make sense to me for a while because, as a more energy-efficient light source, LEDs should make less waste heat. And, in fact, they do.
- However, the LEDs themselves are more sensitive to small amounts of heat than are incandescents or CFLs.
- So the smaller amount of heat that LEDs generate has to be dissipated so as not to diminish the output and life of the bulb.
- That's why many of them have those futuristic (or odd, depending on your view) fins on them.
If you're really concerned, some of the manufacturers publish operating temperature ranges for their LEDs.
But LEDs are typically a good choice for outdoor use.
For more information:
Read "Is there a dimmer that works with LED bulbs?" a Q&A answered by Elizabeth DiSalvo.