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Indianapolis weekend weather

This weekend in Indianapolis, IN, 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 86° across the weekend. Agreement is low - the weekend is genuinely up in the air at this range. Rain chance reaches 80% on at least one model.

Tomorrow

2026-09-19 — every model, side by side
NWSNational Blend (NBM)
86°
Showers
High 86°·Low 68°·Rain 35%
AmericanNOAA GFS
83°
Rain
High 83°·Low 68°·Rain 35%
EuropeanECMWF
87°
Light drizzle
High 87°·Low 68°·Rain 80%

All 3 models land within 4° of each other for this day — that is a forecast you can plan on.

Sun

2026-09-20 — every model, side by side
NWSNational Blend (NBM)
84°
Light drizzle
High 84°·Low 71°·Rain 40%
AmericanNOAA GFS
90°
Thunderstorm
High 90°·Low 68°·Rain 40%
EuropeanECMWF
83°
Light drizzle
High 83°·Low 70°·Rain 45%

The models range from 83° to 90°. Treat the middle of that range as the likely outcome and keep a backup plan.

Where the models disagree

temperature and rain, judged separately
DayTemperatureRain
Today±3°78° to 81°±65%35% to 100% chance
Tomorrow±4°83° to 87°±45%35% to 80% chance
Sun±7°83° to 90°±5%40% to 45% chance
Mon±3°69° to 71°±10%49% to 59% chance
Tue±3°66° to 69°±5%34% to 39% 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 80%. 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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