Weather Forecast Accuracy Last Month (December)

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Weather Forecast Accuracy Last Year (2025)

Weather Changeability for Grafton, Illinois

Average change in

Temperature

Average change in high temperature day-to-day

Last Month:

10.5°

Last Year:

6.3°

Average change in low temperature day-to-day

Last Month:

8.8°

Last Year:

6.9°

Average change in

Precipitation

Chance of dry day after a precip day

Last Month:

100%

Last Year:

62%

Chance of precip day after a dry day

Last Month:

7%

Last Year:

19%

ForecastAdvisor Fact

1.2% of The Weather Channel's low temperature forecasts for Grafton were off by more than 10 degrees last year.

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