Monthly climate averages for Olean, United States. Based on 10-year ERA5 reanalysis data.
Dfb Warm-Summer Continental
Climate OverviewOlean, United States in September has warm conditions, with highs averaging 21.9°C (71°F).
This month falls at the beginning of Autumn.
Daily highs in September gradually drop from around 23°C (74°F) at the start to 20°C (67°F) by month's end.
September sees fairly even rainfall, totalling about 84 mm across the month.
Expect around 9.4h of sunshine at the start of September, decreasing to 7.1h by the end.
The warmest days tend to fall around the 4th, averaging 23.4°C (74°F).
Compared to August, this month is about 3°C cooler with 4 fewer rainy days. Temperatures begin dropping heading into October.
Daily averages based on historical data (2016–2025)
Daytime temperatures around 22°C (71°F) are ideal for full-day outdoor exploration.
Rain usually comes in shorter passing showers rather than all-day rain.
1 of the last 5 yearly records were warmer than this month's long-run average.
| Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 0°C / -7°C | -4°C / -12°C | 15days (87 mm) Wet | 4.5h Fair | 78% Humid | 1.9 Low | Poor | View Details |
| February | 3°C / -6°C | -2°C / -11°C | 13days (87 mm) Wet | 5.8h Fair | 75% Muggy | 3 Moderate | Poor | View Details |
| March | 7°C / -2°C | 4°C / -7°C | 13days (90 mm) Wet | 7.3h Good | 70% Muggy | 4.2 Moderate | Poor | View Details |
| April | 13°C / 3°C | 11°C / 0°C | 15days (114 mm) Wet | 8.4h Good | 70% Muggy | 4.8 Moderate | Poor | View Details |
| May | 19°C / 10°C | 18°C / 8°C | 15days (112 mm) Wet | 9.6h Good | 75% Muggy | 5.8 High | Good | View Details |
| June best | 24°C / 14°C | 24°C / 14°C | 13days (103 mm) Wet | 11.1h Excellent | 75% Muggy | 6.7 High | Excellent | View Details |
| July best | 26°C / 17°C | 28°C / 18°C | 14days (91 mm) Wet | 11.3h Excellent | 76% Humid | 6.9 High | Excellent | View Details |
| August best | 25°C / 17°C | 26°C / 17°C | 13days (101 mm) Wet | 10.4h Excellent | 77% Humid | 5.9 High | Excellent | View Details |
| September best | 22°C / 13°C | 22°C / 13°C | 9days (84 mm) Wet | 8.8h Good | 78% Humid | 5 Moderate | Excellent | View Details |
| October | 16°C / 8°C | 14°C / 5°C | 12days (104 mm) Wet | 6.9h Fair | 78% Humid | 3.4 Moderate | Fair | View Details |
| November | 8°C / 1°C | 4°C / -3°C | 13days (81 mm) Wet | 5.3h Fair | 77% Humid | 2.2 Moderate | Poor | View Details |
| December | 2°C / -4°C | -2°C / -9°C | 15days (85 mm) Wet | 3.9h Poor | 79% Humid | 1.6 Low | Poor | View Details |
Dress in layers — a mix of long sleeves, light sweaters, and a versatile jacket works best for changeable conditions.
A waterproof jacket or compact umbrella is recommended for occasional showers.
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