Sarnia weekend weather
This weekend in Sarnia, 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 21° across the weekend. Agreement is low - the weekend is genuinely up in the air at this range. Rain chance reaches 90% on at least one model. The models agree closely on temperature but split badly on rain (59 points apart), so the rain call is the uncertain part.
Today
2026-10-04 — every model, side by sideEnv. CanadaGEM model
21°
Drizzle
EuropeanECMWF
21°
Drizzle
AmericanNOAA GFS
21°
Cloudy
All 3 models land within under a degree of each other for this day — that is a forecast you can plan on.
Where the models disagree
temperature and rain, judged separatelyThe 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 90%. 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.