You should wrap pipes before temperatures reach freezing, especially if you have any exposed or unheated runs. Starting early in the season is safer than waiting for a specific “cold snap.”
Key temperature thresholds
Most home pros recommend insulating or wrapping outdoor and exposed pipes once the forecast shows temperatures at or below 32°F (0°C). In colder overnight conditions, the risk rises sharply once lows approach the upper teens (around 20°F / −6°C), especially for pipes in attics, crawlspaces, or exterior walls.
Best timing in the season
The ideal time to wrap both hot and cold water pipes is before the first subfreezing nights of the season, rather than after repeated freezes have already occurred. In warmer climates where houses are less protected against cold, it is wise to insulate outdoor and unheated-area pipes as part of fall or early-winter prep, before any hard freeze is forecast.
Which pipes to prioritize
Focus first on pipes that run outdoors, through unheated basements, crawlspaces, garages, attics, or along exterior walls, since these are most likely to freeze. Hose bibs and irrigation lines should be drained, hoses disconnected, and those exposed sections wrapped or covered ahead of freezing temperatures.
