I know that this is going to seem silly to those of you who live in climates that are actually cold... but in Los angeles, where I live, the mornings have been a little chilly -- between 40 and 45 degrees when I start my runs.

I've noticed that when the air is that cold (as opposed to 50-60 degrees, as its been since the summer), that my heartrate is higher than normal. This means that to keep my heartrate at 150ish, I need to drop my mile time down by a minute or more.

Is it common for the body to have a higher heart rate the colder it is? Or is my higher heart rate probably caused by something else, and it's just a fluke that it happened to coincide with the colder weather?

If it is from the weather, can I expect my body to adapt soon?

thanks for the insight :)

It's more common for heart rate to be higher with higher temperatures, but in either case, it sounds like you just need to acclimate or wear more layers. You should adjust your pace to maintain the same level of effort no matter what the conditions, at least for your aerobic runs.