Snow Day Calculator

Total accumulation forecast for the storm, from your forecast provider.
Snow criteria are set by each NWS forecast office: roughly 1-3 in on the Gulf coast, 5-7 in across the Plains, 6-8 in in the northern tier.
0.25 in is the NWS Ice Storm Warning criterion.
Districts set their own cold-closure threshold; -20 to -30 F wind chill is typical in the upper Midwest.
Local time the snow or ice begins accumulating.
Snow-day chance
60 %
Snow Day Calculator
Closure hazard index (0-100)
60.0
Verdict
Likely
Wind chill
18.8 °F
Points from snowfall
45.0
Points from ice
0.0
Points from storm timing
15.0
Points from cold
0.0
NWS product the forecast would meet
The forecast meets the local Winter Storm Warning snow criterion of 6 in.
Snowfall as a multiple of the local warning criterion
1.000
Summary
Likely - a closure hazard index of 60 out of 100 from 6 in of snow, 0 in of ice and a 19 F wind chill.
Worked out from NOAA National Weather Service, Winter Weather Warnings, Watches and Advisories and 2 other sources.
The point scale combining these four factors is a stated heuristic, not a model fitted to historical closures. Treat the number as a ranking of hazard, not as a probability with a track record.
This is an indicator built from a stated point scale, not a validated forecast of any district’s decision. Closures are announced by the school district and hazardous-weather information comes from the National Weather Service; check both.

How this is worked out

5 steps
  1. Snow: 6 in against a local warning criterion of 6 in = 1x, capped at 2x; 45 x 1 = 45 points.
  2. Ice: 0 in against the 0.25 in Ice Storm Warning criterion = 0x, capped at 1.5x; 40 x 0 = 0 points.
  3. Timing: accumulation starts 02:00 - overnight - roads are snow-covered before the morning run; +15 points.
  4. Wind chill: WC = 35.74 + 0.6215(28) - 35.75(1.44544) + 0.4275(28)(1.44544) = 18.77 F; against a -25 F closure threshold that is 25 x min((-25 - 18.77) / 10, 1) clamped at 0 = 0 points.
  5. Index = 45 + 0 + 15 + 0 = 60, clamped to 0-100 = 60.

Results are general information, not financial, tax, legal, medical or engineering advice.