How Our Snow Day Algorithm Works

The Snow Day Predictor is built to give you a fast, clear, and data-driven estimate of how likely your school or college is to close due to winter weather. It uses a combination of real-time forecasts, historical snowfall records, and a custom snow-day algorithm to turn complex weather data into an easy-to-understand percentage.

Where the Data Comes From (APIs We Use)

To make accurate predictions, the tool relies on trusted public weather and geocoding services:

Open-Meteo Forecast API

Used to collect:

  • Hourly temperature
  • Snow, ice, and precipitation
  • Wind speed
  • Weather condition codes
  • Daily high/low temperatures
  • 5-day forecast summary

This provides the real-time weather used in our prediction formula.

Open-Meteo Historical Weather (Archive API)

Used to gather:

  • Up to two years of snowfall data
  • Past days with significant accumulation

This helps us understand how past storms affected potential school closures in your area.

Geocoding APIs

We convert your city, ZIP code, or address into latitude/longitude using:

  1. Open-Meteo Geocoding API (primary)
  2. Maps.co Geocoding API (fallback)

This ensures the tool works anywhere in the world, not only in the U.S. or Canada.

How the Prediction Formula Works

Once your long/lat location is identified and weather is fetched, the Snow Day Predictor uses a multi-factor scoring algorithm. This formula is based on common conditions that influence school closure decisions.

The algorithm analyzes the next 24 hours of hourly weather data and scores these key factors:

Snowfall

  • Heavy snow drastically increases the score
  • Moderate snow adds points
  • Light snow adds only a small chance

Ice Accumulation

Ice is one of the strongest predictors.

  • Any freezing rain/ice codes = high impact
  • Even small amounts can cause dangerous travel

Temperature & Wind Chill

We use the standard wind chill formula:

windChill = 35.74 + 0.6215*T - 35.75*W^0.16 + 0.4275*T*W^0.16
  • Wind chills below 15°F increase the chance
  • Wind chills below 0°F increase it significantly

Wind Speed

High winds reduce visibility and make roads unsafe:

  • Over 30 mph adds a notable effect

Timing of the Storm

If snow or ice occurs between 6–9 AM, the model triggers a “morning impact,” which is one of the most important real-world closure factors.

School Policy Adjustment

You can select:

  • Conservative (rarely closes)
  • Neutral
  • Liberal (closes more easily)

This modifies the final probability to match local patterns.

Final Step

Each factor adds or subtracts points. The total is then clamped between 0–100% to produce a final, clean prediction.