What causes hair to grow quicker in warm weather?

You sweat more, that makes your hair grow faster.

i have a hairy back. maybe you can find a way to stop that!

@superdan. Duct tape

On the contrary, the science doesn’t support your hypothesis. Hair grows at a pretty steady rate, a rate that is really only affected by changes in diet. Hair is a outgrowth of protein, so anything that tunes that process, such as proper hydration and diet, will slightly increase the rate at which your hair grows, but it’s not going to go much past about 1/2 inch per month.

The exception to that rule is pregnant women, who can see upwards of 1 to 1–1/2” inches a month of hair growth.

The only thing I can imagine is that you are making more Vitamin D during the summer months, as you are getting more exposure to UV light. I don’t really know the processes all that well, but perhaps Vitamin D has something to do with hair growth or, alternately, skin elasticity and hydration. The changes in skin between the seasons would explain the prominence of your 5 o’clock shadow, at least.

And @Wizard, there is no correlation between sweat and hair growth.

I significantly sweat more when I have been out playing mens softball all day for weeks straight rather than when I’m off and sit home on the computer. My sweat seems to cause me to grow my hair faster.

From The World of Hair: Hair growth varies with the season as a result of a change in the difference between hair follicles in the growing and shedding phases.

you BBQ more in the summer thus eating more meat which is protien and that makes it grow just a tiny bit faster.

Yeah, but I’m vegetarian, so there goes that theory.

awwwww dammit.
But do you BBQ your veggies? There ya go! BBQ makes hair grow faster.

don’t know why but it happens to me too

Is it not just the fact that you wear shorts, vest tops,
t-shirts etc… therefore your hair is more noticable than it would be if it was covered up???