When to go · Ontario, California
Ontario, California in September
Great month. Inside Ontario, California's best window: Mar–May, Sep–Nov.
Key facts
- Verdict
- Great
- Temperature
- 33°C (91°F)91°F (33°C) / 18°C (64°F)64°F (18°C)
- average high / low
- Rain days
- 1
- Crowds
- Medium
- United States overall
- Prices
- Medium
- United States overall
Verdict
Inside Ontario, California's best window: Mar–May, Sep–Nov.
Is another month better than September?
No other month rates higher than September for Ontario, California in this guide.
Weather in September
- Ontario, CaliforniaHighs around 33 °C (91 °F), lows around 18 °C (64 °F), rain on about 1 dayHighs around 91 °F (33 °C), lows around 64 °F (18 °C), 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 Ontario, California, side by side.
Verdict
Sep: Great
Mar: Great
Daytime high
Sep: 33 °C (91 °F)91 °F (33 °C)
Mar: 22 °C (72 °F)72 °F (22 °C)
Night low
Sep: 18 °C (64 °F)64 °F (18 °C)
Mar: 9 °C (48 °F)48 °F (9 °C)
Rain days
Sep: 1 (better)
Mar: 4
Crowds
Sep: Medium
Mar: Medium
Prices
Sep: Medium
Mar: Medium
Festivals listed
Sep: 1
Mar: 2
September: Inside Ontario, California's best window: Mar–May, Sep–Nov.
March: Inside Ontario, California's best window: Mar–May, Sep–Nov.
Ontario, California: figures are long-term averages from this guide, not a forecast.
What to pack
- Light, breathable clothes, a sun hat and sunscreen