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When to go · Diamond Bar

Diamond Bar in September

Good month. Outside the best window (Mar–May, Oct–Nov). Across United States: After Labor Day the crowds drop and parks stay open; Florida and the Gulf are at hurricane peak.

Key facts

Verdict
Good
Temperature
30°C (86°F) / 17°C (63°F)
average high / low
Rain days
1
Crowds
Medium
United States overall
Prices
Medium
United States overall

Verdict

GoodUnited States month rating

Outside the best window (Mar–May, Oct–Nov). Across United States: After Labor Day the crowds drop and parks stay open; Florida and the Gulf are at hurricane peak.

Is another month better than September?

September is rated good. These months rate higher:

Weather in September

Long-term averages
  • Diamond BarHighs around 30 °C (86 °F), lows around 17 °C (63 °F), rain on about 1 day

Festivals and holidays

Dates as our data lists them. Moving holidays (lunar and Islamic calendars, Easter) shift every year: check the date for your year before you build a trip on it.

  • Labor Day big impact

    1st Monday of September · United States

    End of summer; last big road-trip weekend.

Crowds and prices

Crowds · United States overall
Medium
Prices · United States overall
Medium

United States overall: After Labor Day the crowds drop and parks stay open; Florida and the Gulf are at hurricane peak.

Compare two months

Weather, crowds and prices for any two months in Diamond Bar, side by side.

  • Verdict

    Sep: Good

    Mar: Great (better)

  • Daytime high

    Sep: 30 °C (86 °F)

    Mar: 21 °C (70 °F)

  • Night low

    Sep: 17 °C (63 °F)

    Mar: 9 °C (48 °F)

  • Rain days

    Sep: 1 (better)

    Mar: 5

  • Crowds

    Sep: Medium

    Mar: Medium

  • Prices

    Sep: Medium

    Mar: Medium

  • Festivals listed

    Sep: 1

    Mar: 2

September: Outside the best window (Mar–May, Oct–Nov). Across United States: After Labor Day the crowds drop and parks stay open; Florida and the Gulf are at hurricane peak.

March: Inside Diamond Bar's best window: Mar–May, Oct–Nov.

Diamond Bar: figures are long-term averages from this guide, not a forecast.

What to pack

  • Light, breathable clothes, a sun hat and sunscreen

Build the full packing list for your trip →

Across United States in September →