Greater Boston
Boston's winter weather is decided offshore, where the track of a coastal storm determines whether the city gets a foot of snow or a cold rain. The estimate below is loaded with live Boston forecast data.
Live Boston forecast estimate
Enter a location to compare tomorrow's snow, ice, temperature, wind and morning timing.
Local conditions
Boston sits on a harbour open to the Atlantic, and the water offshore holds enough warmth through early winter to modify air arriving over it. In a nor'easter, the storm's centre position decides everything: a track well southeast of the city keeps cold air in place and produces heavy snow with strong northeast wind, while a track closer in draws marine air over the coast and changes snow to sleet and rain. Move twenty miles inland and up in elevation and the same storm produces reliably more snow, which is why Boston forecasts should never be applied to the wider region without checking.
What actually drives a decision
Boston's marginal temperatures produce dense, water-laden snow that clings to trees and lines. When it comes with the strong onshore wind typical of a nor'easter, outages follow, and a school without heat or power cannot open regardless of how clear the roads are. That failure mode is outside the weather model, so treat a wet-snow-plus-wind forecast as more disruptive than the score alone.
Many Greater Boston districts are geographically small with significant numbers of students walking or using the MBTA. Sidewalk and crossing conditions before sunrise carry real weight in the decision, and those surfaces are cleared later than main roads.
When a storm's peak wind coincides with astronomical high tide, specific shoreline roads can flood and close while the rest of a district is unaffected. This is a separate hazard the calculator does not model; check National Weather Service coastal flood products directly.
Nor'easters generate their own wind, and blowing snow in exposed coastal areas can cut visibility sharply even when accumulation is moderate. The wind chill factor captures the exposure component of this, but visibility is not directly measured by the model.
The forecast for the coordinates above is scored against six weighted factors: snow and ice, temperature, wind chill, morning timing, area and routes, and school level. Around Boston the rows that most often carry the number are snow and ice, wind chill, morning timing. Every factor appears in the result with its own value, score bar and published weight, so a percentage is never presented without the reasoning behind it. The methodology page documents each threshold, and the accuracy and limitations page sets out what the model cannot observe.
This site does not publish closure thresholds for any school system, because those are operational judgements rather than published numbers. What it can do is point you at the organisations that actually decide. Around Boston, MA those include:
Treat the estimate on this page as a reason to prepare and to keep checking, never as an announcement. A school system can close buildings, delay the start, cancel transportation only, dismiss early or move to a different learning format, and those outcomes are not interchangeable.
Primary sources for weather warnings and road conditions covering Boston. School decisions still come from the systems listed above.
Boston questions
The estimate covers the forecast, not the call. Boston Public Schools and each surrounding district decide independently, and in a marginal coastal storm the city and the towns west of it regularly reach different conclusions about the same system.
Ocean water moderates temperature along the coast, so a storm that pulls marine air inland changes snow to sleet or rain near the shore first. Communities farther inland and higher above sea level stay below freezing longer and keep all snow.
No. The model scores forecast weather and broad local context. Power loss from heavy wet snow and wind is a separate operational failure that can close a building on its own, which is why the result page states plainly what the model cannot see.
Check the evening before to prepare, then again early in the morning. Coastal storm tracks are frequently revised inside 24 hours, and precipitation type near the shore can change with a small shift.
Still deciding what to do with the number? Read how schools make the final call and the guide to the best times to check a forecast.