O'Fallon weather in June

In June, O'Fallon sees average daytime highs of 84°F and overnight lows near 66°F, with 4.0 in of rain across 11.1 wet days and about 14.7 hours of daylight. It is the 3rd-warmest and 3rd-wettest month of the year here.

Highs climb over the month, from about 80°F in the first days to 86°F by the end. The sky is clear or mostly clear about 35% of the time in June, and the air most often feels muggy.

Daylight stretches from about 14 h 30 min at the start of June to 14 h 42 min by month's end. Set against the rest of the year, June is O'Fallon's 5th-clearest and 9th-windiest month. For the whole year in context, see O'Fallon's year-round climate.

Daytime high
84°
3rd warmest
Overnight low
66°
10th coldest
Rainfall
4.0 in
11.1 wet days
Daylight
14 h 42 min
4:42 AM – 7:24 PM
Cloud cover
55%
5th clearest
Wind
6 mph
9th windiest
Solar energy
6.42 kWh/m²
Travel score
5.5
out of 10

O'Fallon is city in St. Charles County, Missouri, United States.

Density
1,105/km²
people per km²
Founded
1856

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

Temperature in June

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 80°F in the first days to 86°F by the end.

A typical June day in O'Fallon reaches about 84°F in the afternoon and slips back to 66°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 75°F and 92°F. Set against its neighbours, June runs about 9°F warmer than May and about 4°F cooler than July.

50°60°70°80°90°151015202530
Avg high (°F)Avg low (°F)
18063
28063
38063
48164
58164
68164
78265
88265
98265
108365
118366
128366
138366
148467
158467
168467
178567
188567
198568
208568
218568
228568
238668
248668
258668
268669
278669
288669
298669
308669

How June really feels in O'Fallon

Once humidity and wind are folded in, June 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

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

O'Fallon weather by month

How June compares with the rest of the year at a glance. June is the 3rd-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan40° / 24°2.57.739.60.0
Feb44° / 28°2.47.62.910.50.8
Mar55° / 37°3.610.61.411.73.5
Apr66° / 47°4.511.30.2135.8
May75° / 57°4.913.3014.16.3
Jun84° / 66°4.011.1014.75.5
Jul87° / 70°3.29.9014.44.6
Aug86° / 67°3.09.2013.55.2
Sep79° / 59°3.27.6012.37.1
Oct67° / 48°3.38.50116.6
Nov54° / 37°3.58.30.89.93.5
Dec43° / 28°2.47.72.29.30.6

Cloud cover in June

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 35% of the time in June.

Beyond those clear spells, partly cloudy skies cover about 18% of June, with mostly cloudy or overcast conditions the remaining 48%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14555
24555
34654
44654
54852
64852
74951
84951
94951
105149
115149
125248
135347
145347
155446
165446
175545
185545
195545
205644
215644
225644
235644
245644
255545
265644
275644
285644
295644
305743

Chance of precipitation in June

Any precipitation

O'Fallon gets around 4.0 in of rain over 11.1 wet days in June. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 38% and peaks near 40% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
140
240
339
439
538
638
738
838
938
1038
1138
1238
1338
1438
1538
1638
1738
1838
1937
2037
2137
2237
2337
2436
2536
2636
2736
2836
2936
3036

Humidity in June

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, June lands in the muggy band about 34% of days. Sticky, muggy-or-worse air turns up on roughly 52% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
12519213150
22320213150
32220213260
42120213260
52020213370
61919213380
71819213390
817182134100
915182134110
1014172234130
1113162235140
1212152235150
1311142236160
1410142236180
159132237190
169122237200
178122237210
188122237210
197122237220
207122237230
216122236230
226122236240
236132236240
245132135250
255132135250
265142134261
274142133271
284142133281
294142132291
304142131301

Wind in June

Winds average 6 mph in June.

Across June, daily wind ranges from about 6 mph on the calmest days to 6 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
276calm
286calm
296calm
306calm

Sunrise & sunset in June

DaylightNight

Daylight runs from about 14 h 30 min at the start of June to 14 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 12 minutes over June. Sunrise moves from 4:45 AM to 4:45 AM, and sunset from 7:16 PM to 7:27 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
114.54:457:16
214.54:457:16
314.54:447:17
414.64:447:18
514.64:447:18
614.64:437:19
714.64:437:20
814.64:437:20
914.64:437:21
1014.64:427:21
1114.74:427:22
1214.74:427:22
1314.74:427:23
1414.74:427:23
1514.74:427:24
1614.74:427:24
1714.74:427:24
1814.74:427:25
1914.74:427:25
2014.74:427:25
2114.74:427:26
2214.74:437:26
2314.74:437:26
2414.74:437:26
2514.74:437:26
2614.74:447:27
2714.74:447:27
2814.74:447:27
2914.74:457:27
3014.74:457:27

Solar energy in June

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in June, about 6.42 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 1.92 kWh/m² to a high of 6.42 kWh/m² in June across the year — June's 6.42 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
16.1Intense
26.1Intense
36.1Intense
46.1Intense
56.2Intense
66.2Intense
76.2Intense
86.2Intense
96.3Intense
106.3Intense
116.3Intense
126.3Intense
136.4Intense
146.4Intense
156.4Intense
166.5Intense
176.5Intense
186.5Intense
196.5Intense
206.5Intense
216.5Intense
226.5Intense
236.6Intense
246.6Intense
256.6Intense
266.6Intense
276.6Intense
286.6Intense
296.6Intense
306.6Intense
Planning a trip in June

Is June a good time to visit O'Fallon?

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

5.5
Sightseeing
5th-best month of the year
6.6
Beach & pool
4th-best month of the year

June is a reasonable time to visit O'Fallon for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for O'Fallon in June

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

In June, O'Fallon sees daytime highs around 84°F and nights near 66°F. Pack light clothes and sun protection. Worth having: rain gear. About 11 days see rain.

light clothessun protectionrain gear

UV index in O'Fallon in June

LowModerateHighVery highExtreme

Clear-sky midday UV in June peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in O'Fallon peaks around June 22 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJun 22UV 9Jan 1UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr7High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep7High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in O'Fallon in June

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in O'Fallon is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (October, 7 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1616 µg/m³Oct 237 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb11Good
Mar11Good
Apr10Good
May13Moderate
Jun14Moderate
Jul17Moderate
Aug14Moderate
Sep11Good
Oct7Good
Nov7Good
Dec8Good
Location & terrain

Where is O'Fallon?

O'Fallon sits at 38.8°N, 90.7°W, 541 ft above sea level, in United States. The nearest listed city is Saint Peters, 3.7 mi away.

Topography around O'Fallon

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

Within 2 miles, the terrain around O'Fallon has only modest variations in elevation — a maximum elevation change of 207 ft around an average of 535 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 413 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 928 ft.

The land around O'Fallon is covered by trees (43%), artificial surfaces (34%) and grassland (20%) within 2 miles, trees (41%) and cropland (24%) within 10 miles, and trees (52%) and cropland (31%) within 50 miles.

2 miles
207 ft
10 miles
413 ft
50 miles
928 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
June weather nearby: Saint Peters 3.7 mi · Wentzville 8.1 mi · Saint Charles 12 mi · Chesterfield 12 mi · Wildwood 16 mi · Maryland Heights 16 mi · Ballwin 17 mi · Hazelwood 18 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 O'Fallon (38.8106°, -90.6998°, elevation 541 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).