Ice dam risk in Atchison, KS
Ice dams in Atchison, KS: how often
5.7 dam days a winter
Moderate risk. On an ordinary house in Atchison, conditions for an ice dam come on about 5.7 days in a normal winter, mostly in January and February.
Atchison averages 17 inches of snow a year and about 23 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 Atchison
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 3.5 | Low |
| Typical, some insulation, not air-sealed | 5.7 | Moderate |
| Older or poorly insulated, warm attic | 8.4 | Moderate |
Sealing and insulating a typical attic takes out about 2.2 days a winter here. It drops the risk from moderate to low.
What to do about ice dams in Atchison
- Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.
Which to spend on first: air sealing or heat cable.
Atchison winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 5.0 | 8.0 | 2.5 |
| February | 4.8 | 6.5 | 1.6 |
| March | 1.8 | 2.2 | 0.3 |
| April | 0.4 | 0.2 | 0.0 |
| October | 0.3 | 0.1 | 0.0 |
| November | 0.9 | 0.6 | 0.1 |
| December | 3.8 | 5.0 | 1.3 |
Atchison next to nearby towns
Atchison ranks 3 of 38 Kansas cities here for ice-dam days, behind Salina at 5.8 days.
- Leavenworth, KS 20 mi, 4.7 days
- St. Joseph, MO 22 mi, 8.2 days
- Lansing, KS 26 mi, 4.7 days
- Smithville, MO 32 mi, 5.2 days
- Kansas City, KS 37 mi, 4.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Atchison, 1.6 miles from Atchison. 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.