Grantham Weather Forecast

    • 52
    • 74

    Mostly Cloudy

    • 64
    • 75

    Rain Showers

    • 53
    • 78

    Slight Chance Rain Showers

    • 48
    • 69

    Mostly Sunny

    • 53
    • 75

    Partly Sunny

    • 55
    • 76

    Partly Sunny

Today 8 Sep Sullivan

Partly sunny. Highs in the mid 70s. Light and variable Winds, becoming northwest around 10 Mph in the afternoon.

Tonight 8 Sep Sullivan

Partly cloudy in the Evening, then becoming mostly cloudy. Lows in the lower 50s. Light and variable Winds.

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Grantham Temperature Statistics

September Temperature

Lebanon Municipal Airport (12.4 miles)

  • Lowest 5 September, 2026

    55 °F

  • Average September

    65 °F

  • Highest 4 September, 2026

    80.1 °F

Climate (2021–2026)

Lebanon Municipal Airport (12.4 miles)

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  • Average Low 2021–2026

    37.9 °F

  • Average 2021–2026

    48.7 °F

  • Average High 2021–2026

    59.7 °F
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