The rule of thumb in American Red Cross guidance is that pipes can freeze and burst when outdoor temperatures reach 20 degrees or lower. Where the pipe runs matters as much as the number. This checker combines the forecast low, the pipe location and the insulation into one risk level, and tells you what to do about it.
Check one pipe
Water still spreading? Do not wait for it to stop on its own.
Call (223) 245-0005How the checker scores a pipe
| Input | Points |
|---|---|
| Forecast low above 32 degrees | 0 (risk capped at Low) |
| 26 to 32 degrees | 1 |
| 21 to 25 degrees | 2 |
| 11 to 20 degrees | 3 |
| 10 degrees or lower | 4 |
| Heated interior wall / heated basement | 0 / 1 |
| Exterior wall / crawlspace | 3 / 3 |
| Unheated garage / outdoor hose bib | 4 / 4 |
| Insulation good / some / none | 0 / 1 / 2 |
Total 0 to 2 is Low, 3 to 5 is Moderate, 6 to 7 is High and 8 or more is Severe. The scoring is our own rule of thumb built around the 20-degree guidance. It is not a measurement of your pipe.
How often a Mechanicsburg-area night reaches those numbers
In NOAA daily records for the Middletown-Harrisburg station from 1991 through 2020, the low reached 20 degrees or below on about 28 nights a year and 10 degrees or below on about 5 nights a year. The median last spring freeze was April 9 and the median first fall freeze was November 4. These are our calculations from daily data, so treat the dates as typical, not guaranteed.
Read more in which pipes in Central PA homes freeze first and the winter pipe checklist. If a pipe has already split, see frozen and burst pipe cleanup, or call (223) 245-0005.
Risk checker questions
What temperature do pipes freeze at?
Guidance based on American Red Cross material puts the risk at 20 degrees or lower outside. Wind, insulation and pipe location matter, and a pipe inside a heated wall can stay above freezing when it is 25 outside.
Does the checker work for the whole house?
It rates one pipe at a time. Run it for the most exposed pipe in each space, such as the exterior-wall kitchen line, the crawlspace and the hose bib.
Should I let the faucet drip?
Often yes, on the coldest nights and for pipes on exterior walls. A small steady stream moves water and relieves pressure. It is one step, not a guarantee.
What if the pipe has already frozen?
Keep the heat on, open the faucet and call a plumber. Do not use a flame. If it has split, close the main shut-off and call us.
