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Hamilton weekend weather

This weekend in Hamilton, Ontario, model by model. Weekend forecasts are far enough out that the models often split - so we show you where.

Weekend

The models centre on about 19° across the weekend. Agreement is medium - plausible, but worth re-checking closer to the day. Rain chance reaches 76% on at least one model.

Today

2026-09-19 — every model, side by side
Env. CanadaGEM model
21°
Light drizzle
High 21°·Low 15°·Rain 14%
EuropeanECMWF
17°
Cloudy
High 17°·Low 16°·Rain 45%
AmericanNOAA GFS
20°
Cloudy
High 20°·Low 13°·Rain 17%

The models range from 17° to 21°. Treat the middle of that range as the likely outcome and keep a backup plan.

Tomorrow

2026-09-20 — every model, side by side
Env. CanadaGEM model
21°
Drizzle
High 21°·Low 15°·Rain 43%
EuropeanECMWF
19°
Light rain
High 19°·Low 16°·Rain 76%
AmericanNOAA GFS
19°
Cloudy
High 19°·Low 15°·Rain 53%

All 3 models land within 2° of each other for this day — that is a forecast you can plan on.

Where the models disagree

temperature and rain, judged separately
DayTemperatureRain
Today±4°17° to 21°±31%14% to 45% chance
Tomorrow±2°19° to 21°±33%43% to 76% chance
Mon±2°15° to 17°±14%0% to 14% chance
Tue±3°15° to 18°±20%5% to 25% chance
Wed±2°15° to 17°±15%18% to 33% chance

The models often agree on temperature and still split on rain, and rain is usually what decides whether a plan survives. A wide rain range means the shower is genuinely uncertain, not that the forecast is wrong.

Common questions

Will it rain this weekend?
At least one model puts the weekend rain chance as high as 76%. Weekend forecasts sit far enough ahead that models frequently disagree on showers - when they do, no single app can honestly tell you it will or will not rain.
How reliable is a weekend forecast?
It depends how far away the weekend is. Forecast error grows steadily with lead time, so a Saturday forecast made on Friday is far stronger than one made the previous Monday. The honest signal is model agreement: when they converge the forecast is solid, and when they spread the weekend is genuinely uncertain.

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