Ice dam risk in Derby, KS
Ice dams in Derby, KS: how often
2.8 dam days a winter
Low risk. On an ordinary house in Derby, conditions for an ice dam come on about 2.8 days in a normal winter, mostly in January and December.
Derby averages 8 inches of snow a year and about 12 days with snow on the ground. Most of it comes and goes within a few days. The conditions that make a dam need all three at once: snow, cold at the eave and heat above it.
What your attic does to that number in Derby
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 2.1 | Low |
| Typical, some insulation, not air-sealed | 2.8 | Low |
| Older or poorly insulated, warm attic | 3.6 | Low |
The attic matters less in Derby than in colder towns: there are only 0.7 days a winter between a typical attic and a sealed one.
What to do about ice dams in Derby
- Check the gutters before the first snow and clear them, so meltwater has somewhere to go. If you see icicles thicker than a finger along the eave after a storm, that is the early sign to look at the attic.
Snowy places are not always the worst: why snowfall misleads.
Derby winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 2.1 | 3.3 | 0.9 |
| February | 2.3 | 3.2 | 0.8 |
| March | 0.5 | 1.4 | 0.2 |
| November | 0.2 | 0.7 | 0.1 |
| December | 3.0 | 3.2 | 0.8 |
Derby next to nearby towns
Derby ranks 27 of 38 Kansas cities here for ice-dam days, behind Salina at 5.8 days.
- Haysville, KS 5 mi, 2.8 days
- Wichita, KS 10 mi, 2.6 days
- Andover, KS 11 mi, 2.8 days
- Bel Aire, KS 15 mi, 2.6 days
- Winfield, KS 27 mi, 2.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Haysville 3SE, 4.2 miles from Derby. A dam day is a day with snow on the roof and freezing at the eave while heat or sun melts the snow above it. This describes a normal winter, not this one.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.