How low do temperatures have to be for pipes to freeze?

If you are concerned about your pipes bursting in below-freezing temperatures, check out the Insurance Institute for Business and Home Safety. It's an excellent source of information.

The temperature alert threshold for pipes to burst is 20 degrees. 

The southern United States is more likely to have unprotected pipes because we rarely have temperatures in the 20s. 

When there is a wind chill,  the wind chill will accelerate the ice blockage.

*** A note about pools when the temperatures get into the lower 20s.***  I spoke with a pool expert and he told me let the pools pump run.  The pool won’t freeze and letting it run will keep above freezing water flowing through the pipes.