Metal will expand with heat and contract in cold
On the other hand, my most noteworthy outage came one winter day, when I awoke to my overhead drop line snapping, with a very noisy "twang".
It turns out that overnight had seen serious snowstorms in the midlands, bad enough to take out power over a widespread region. The snow was of a particular "sticky" type that stuck to phone lines, and weighed each down heavily. All of the longer lines from the pole bent low, dropping down to below head height - massive expansion in cold weather! It was very weird!
What I think happened to my line was this: All those other lines added enough weight to the other side of the pole that it bent that way - stretching my short line beyond its elastic limit. Snap-twang!
I didn't even need to report anything to get BT to fix the line; the neighbour's line went too, and BT just fixed mine at the same time as theirs. Good job, as I had to disappear off down south that weekend.