The Weather Cancellation Calculator assists emergency managers, school administrators, and safety officers in quantifying the risk posed by incoming winter weather systems. This calculator is based on entirely on the NIU-Winter Weather Model for School Closures at https://www.niu.edu/emergencyinfo/weather/_pdf/NIU-Severe-Weather-Evaluation-tool.pdf
INSTRUCTIONS: Choose units and enter the following:
Weather Cancellation Recommendations (CS): The calculator will compute a cancelation score and return one of three recommendations as follows with the score.
To apply the NIU Severe Weather Evaluation Tool, follow these steps:
1.Obtain Forecast Data
Collect forecast temperatures, wind speeds, snowfall/sleet amounts, freezing rain/ice accumulations, and expected visibility conditions for the relevant academic day.
2. Enter Applicable Values
For each weather category (temperature, wind, snow/sleet, freezing rain/ice, and other factors).
3. Interpret Total Score
The equation will calculate the total score.
After computing the total:
Emergency management often suffers from "subjective bias" during weather events. Decision-makers may be overly cautious or dangerously complacent based on personal experience. The Weather Cancellation Calculator is a quantitative decision-support matrix developed by Northern Illinois University (NIU). It provides a standardized method for emergency managers and administrators to assess meteorological threats and determine the appropriate level of institutional response.. The tool is designed to quantify forecasted severe weather conditions—such as cold temperatures, high winds, snow, freezing rain, and fog—by assigning numerical values to each condition. These values are totaled to produce a severity score that aids discussions about whether the university should close or suspend regular operations.
To apply the NIU Severe Weather Evaluation Tool, follow these steps:
1.Obtain Forecast Data
Collect forecast temperatures, wind speeds, snowfall/sleet amounts, freezing rain/ice accumulations, and expected visibility conditions for the relevant academic day.
2. Enter Applicable Values
For each weather category (temperature, wind, snow/sleet, freezing rain/ice, and other factors).
3. Compute Total Score
The equation will calculate the total score.
The tool assigns numerical values based on conditions forecast for the operational day. Higher values indicate more severe weather conditions.
Certain conditions automatically assign a 100-point score if forecast or confirmed. Each of these triggers the maximum automatic value:
–10 °F to –14 °F 25
–15 °F to –19 °F 50
–20 °F to –21 °F 75
–22 °F to –26 °F 100
(Scores reflect severity of cold conditions.)
10–15 mph 15
15–20 mph 20
20–25 mph 25
26–30 mph 30
31–40 mph 40
41–50 mph 60
51–60 mph 70
61–70 mph 80
71–80 mph 100
(Scores rise with increasing wind intensity.)
2–4 inches 25
5 inches 30
6 inches 40
7 inches 50
8 inches 60
9 inches 75
10 inches 80
11 inches 85
≥12 inches 100
(Accumulative snow and sleet amount increases the severity score.)
Trace to 0.10″ 50
0.10″–0.25″ 70
Over 0.25″ 100
(Higher ice accumulations are particularly hazardous.)
The tool assigns smaller values for additional issues such as dense fog or low visibility while it is precipitating (e.g., 15 points).
After computing the total:
Although the scoring model provides guidance, it is not a policy mandate; the final decision remains the responsibility of the organization
See Also
Weather-related safety procedures at NIU (watches, warnings, campus guidance).
National Weather Service severe weather definitions and hazard outlooks.
Northern Illinois University. (n.d.). NIU-Severe Weather Evaluation Tool: NIU-Winter Weather Model for School Closures [PDF]. Retrieved from https://www.niu.edu/emergencyinfo/weather/_pdf/NIU-Severe-Weather-Evaluation-tool.pdf
*narrative created with the assistance of GAI