Hamilton weather in September

In September, Hamilton sees average daytime highs of 77°F and overnight lows near 58°F, with 2.7 in of rain across 8 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 12th-wettest month of the year here.

Highs ease over the month, from about 81°F in the first days to 73°F by the end. The sky is clear or mostly clear about 42% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Hamilton's 1st-clearest and 10th-windiest month. For the whole year in context, see Hamilton's year-round climate.

Daytime high
77°
4th warmest
Overnight low
58°
9th coldest
Rainfall
2.7 in
8 wet days
Daylight
12 h 18 min
6:25 AM – 6:40 PM
Cloud cover
49%
1st clearest
Wind
6 mph
10th windiest
Solar energy
4.58 kWh/m²
Travel score
7.2
out of 10

Hamilton is city in Butler County, Ohio, United States.

Density
1,092/km²
people per km²
Founded
1794

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 81°F in the first days to 73°F by the end.

A typical September day in Hamilton reaches about 77°F in the afternoon and slips back to 58°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 67°F and 87°F. Set against its neighbours, September runs about 6°F cooler than August and about 12°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18264
28163
38163
48163
58062
68062
78062
88061
97961
107960
117960
127860
137859
147859
157758
167758
177757
187657
197657
207656
217556
227555
237455
247455
257454
267354
277353
287353
297253
307252

How September really feels in Hamilton

Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Hamilton weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan38° / 24°3.310.34.39.50.0
Feb41° / 26°2.99.23.710.50.3
Mar51° / 34°4.111.3211.72.5
Apr64° / 45°4.712.50.5135.2
May73° / 55°4.612.8014.16.2
Jun81° / 64°4.212.3014.75.9
Jul84° / 67°3.611.2014.55.4
Aug83° / 66°3.29.9013.56.0
Sep77° / 58°2.78012.37.2
Oct65° / 46°3.08.40.1116.0
Nov52° / 37°3.39.10.89.82.8
Dec42° / 29°3.610.139.30.2

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 42% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 42%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15941
25941
35941
46040
56040
66040
76040
86040
96040
105842
115842
125842
135842
145644
155644
165545
175644
185644
195644
205743
215743
225743
235743
245842
255941
265941
275941
285941
296040
305941

Chance of precipitation in September

Any precipitation

Hamilton gets around 2.7 in of rain over 8 wet days in September, the driest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 27% and peaks near 28% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
127
227
327
427
527
626
726
826
926
1026
1126
1226
1326
1427
1527
1627
1727
1828
1928
2028
2128
2228
2328
2428
2527
2627
2726
2826
2925
3024

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the dry band about 42% of days. Sticky, muggy-or-worse air turns up on roughly 18% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11725212611
21826202610
3202620259
4212720248
5232719238
6242819227
7262819226
8282818215
9302818204
10322818193
11332818183
12352718182
13372718172
14392618161
15412517161
16432517151
17452416141
18472316131
19492215121
20512215120
21542114110
22562014100
23572013100
2459191390
2561191280
2662181280
2764181170
2865171170
2966161170
3068161060

Wind in September

Winds average 6 mph in September.

Across September, daily wind ranges from about 6 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
277calm
287calm
297calm
307calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over September. Sunrise moves from 6:11 AM to 6:38 AM, and sunset from 7:05 PM to 6:17 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.96:117:05
212.96:127:04
312.86:137:02
412.86:147:00
512.76:156:59
612.76:156:57
712.66:166:55
812.66:176:54
912.66:186:52
1012.56:196:50
1112.56:206:49
1212.46:216:47
1312.46:226:45
1412.36:236:44
1512.36:246:42
1612.36:256:40
1712.26:266:38
1812.26:276:37
1912.16:286:35
2012.16:296:33
2112.06:306:32
2212.06:316:30
2311.96:326:28
2411.96:336:27
2511.96:346:25
2611.86:356:23
2711.86:366:22
2811.76:376:20
2911.76:376:18
3011.66:386:17

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.58 kWh/m².

For context, solar energy here swings from a low near 1.67 kWh/m² to a high of 6.21 kWh/m² in June across the year — September's 4.58 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.1Bright
25.1Bright
35.0Bright
45.0Bright
55.0Bright
64.9Bright
74.9Bright
84.9Bright
94.8Bright
104.8Bright
114.8Bright
124.7Bright
134.7Bright
144.7Bright
154.6Bright
164.6Bright
174.5Bright
184.5Bright
194.5Bright
204.4Bright
214.4Bright
224.3Bright
234.3Bright
244.3Bright
254.2Bright
264.2Bright
274.1Bright
284.1Bright
294.0Bright
304.0Bright
Planning a trip in September

Is September a good time to visit Hamilton?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

7.2
Sightseeing
1st-best month of the year
6.4
Beach & pool
3rd-best month of the year

September is one of the better times to visit Hamilton for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Hamilton in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Hamilton sees daytime highs around 77°F and nights near 58°F. Worth packing: light clothes, rain gear and sun protection. About 8 days see rain.

light clothesrain gearsun protection

UV index in Hamilton in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Hamilton peaks around June 21 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJun 21UV 9Dec 22UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov3Moderate
Dec2Low

Air quality in Hamilton in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Hamilton is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 8 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1217 µg/m³Oct 228 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb12Good
Mar12Good
Apr12Good
May14Moderate
Jun16Moderate
Jul17Moderate
Aug14Moderate
Sep11Good
Oct8Good
Nov8Good
Dec9Good
Location & terrain

Where is Hamilton?

Hamilton sits at 39.4°N, 84.6°W, 594 ft above sea level, in United States. The nearest listed city is Fairfield, 3.7 mi away.

Topography around Hamilton

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Hamilton.

Within 2 miles, the terrain around Hamilton has only modest variations in elevation — a maximum elevation change of 308 ft around an average of 643 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 558 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 876 ft.

The land around Hamilton is covered by trees (34%), artificial surfaces (34%) and grassland (22%) within 2 miles, trees (39%) and grassland (31%) within 10 miles, and trees (41%) and cropland (39%) within 50 miles.

2 miles
308 ft
10 miles
558 ft
50 miles
876 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Fairfield 3.7 mi · Forest Park 8.1 mi · Middletown 12 mi · Oxford 12 mi · White Oak 13 mi · Mason 14 mi · Norwood 17 mi · Cincinnati 19 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Hamilton (39.3995°, -84.5613°, elevation 594 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).