You really MUST have an alternate method from a Bic lighter.

Bic's run on butane which has a vapor point of 0.4C. So they will not work below freezing because the butane can't vaporize.

Thus having a firesteel is a good alternative. It works at any temperature.

OK, you MAY be able to get a Bic to work in below freezing temps if you warm it up using your body heat--in an inside pocket or better, in your arm pit. But you aren't going to be able to do this if you have hypothermia.

In warm weather a Bic is simpler and easier than any other method so it is still my method of choice.