Here the main concern is termites.  I have seen stretches of ten or fifteen poles in a row snap from a high wind; termites had eaten out the center of the poles so that when one pole let go the others fell down too.  Our lines sag from heat, but the power lines are higher than the cable, so the cable generally gets hit by the excavator being hauled down the road before the power line.
Ice is not fun.  Near my wife's home in New York they had a severe ice storm about fifteen years ago that took the tops out of many trees.  The maple producers still have trees dying from the damage.