Is the Charge Affected by the Cold?

I have had a Fitbit Flex for over 6 months; but, lately it seems to be losing its charge.

I am wondering if it has to do with the cold weather - I used to be able to hold the charge for 6 to 7 days; but, lately in 2 days I am only half charged.  I guess I won't really know if that is the case for a few more weeks when the weather is consistently warmer every day.

This week will just be a hoax as the temperature is to be in the 50's on Friday and Saturday; but, they are already stating the terminology "polar vortex" again for the end of next week.

As I know that the batteries in mobile phones are susceptible to the cold weather I can only assume that the same is affecting my Fitbit Flex - for now I will just charge it every other day.