Newton weather in September

In September, Newton sees average daytime highs of 75°F and overnight lows near 55°F, with 3.8 in of rain across 8.3 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 79°F in the first days to 70°F by the end. The sky is clear or mostly clear about 47% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Newton's 1st-clearest and 9th-windiest month. For the whole year in context, see Newton's year-round climate.

Daytime high
75°
4th warmest
Overnight low
55°
9th coldest
Rainfall
3.8 in
8.3 wet days
Daylight
12 h 18 min
5:58 AM – 6:15 PM
Cloud cover
46%
1st clearest
Wind
9 mph
9th windiest
Solar energy
4.62 kWh/m²
Travel score
7.2
out of 10

Newton is city in and the county seat of Jasper County, Iowa, United States.

Density
519/km²
people per km²
Founded
1850

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 79°F in the first days to 70°F by the end.

A typical September day in Newton reaches about 75°F in the afternoon and slips back to 55°F overnight — a 20°F spread between the day's warmth and the night's chill. On most days the high lands between 64°F and 85°F. Set against its neighbours, September runs about 6°F cooler than August and about 13°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18060
27960
37960
47959
57859
67858
77858
87858
97757
107757
117656
127656
137655
147555
157555
167454
177454
187453
197353
207353
217352
227252
237251
247251
257151
267150
277150
287049
297049
306949

How September really feels in Newton

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.

Newton weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan29° / 13°1.36.64.89.30.0
Feb34° / 17°1.66.64.710.30.0
Mar47° / 29°2.78.82.711.71.6
Apr60° / 40°4.411.2113.14.7
May71° / 52°5.413.50.114.36.0
Jun80° / 62°5.211.60156.3
Jul83° / 65°3.910014.76.0
Aug81° / 63°4.09.4013.76.7
Sep75° / 55°3.88.3012.37.2
Oct62° / 42°2.98.30.410.95.5
Nov47° / 30°2.26.91.69.61.7
Dec34° / 19°1.66.44.390.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 47% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 13% of September, with mostly cloudy or overcast conditions the remaining 40%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16634
26634
36634
46634
56634
66535
76436
86436
96337
106238
116139
126040
135941
145941
155842
165842
175743
185644
195644
205644
215743
225743
235743
245842
255842
265842
275842
285941
295941
305941

Chance of precipitation in September

Any precipitation

Newton gets around 3.8 in of rain over 8.3 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 28% and peaks near 31% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
125
225
325
425
525
626
726
827
927
1028
1128
1229
1330
1430
1530
1631
1731
1831
1931
2030
2130
2230
2329
2429
2529
2628
2728
2828
2928
3027

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 51% of days. Sticky, muggy-or-worse air turns up on roughly 14% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1232322248
2252322237
3272421217
4292421196
5322421185
6342420175
7362420164
8382419154
9402419153
10422318143
11432317143
12452317132
13472216132
14492216122
15512115121
16522115111
17542014111
18562013101
19581912101
2060191290
2162181190
2264181080
2366171070
246717970
256916960
267115860
277215850
287414750
297514740
307713640

Wind in September

Winds average 9 mph in September.

Across September, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
139light breeze
149light breeze
159light breeze
169light breeze
179light breeze
189light breeze
199light breeze
209light breeze
219light breeze
229light breeze
239light breeze
249light breeze
259light breeze
269light breeze
279light breeze
289light breeze
299light breeze
309light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours 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 84 minutes over September. Sunrise moves from 5:42 AM to 6:13 AM, and sunset from 6:41 PM to 5:50 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:426:41
212.95:436:40
312.95:456:38
412.85:466:36
512.85:476:34
612.75:486:33
712.75:496:31
812.75:506:29
912.65:516:27
1012.65:526:26
1112.55:536:24
1212.55:546:22
1312.45:556:20
1412.45:566:18
1512.35:576:17
1612.35:586:15
1712.25:596:13
1812.26:006:11
1912.16:016:09
2012.16:036:08
2112.06:046:06
2212.06:056:04
2311.96:066:02
2411.96:076:00
2511.86:085:59
2611.86:095:57
2711.76:105:55
2811.76:115:53
2911.76:125:51
3011.66:135:50

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.62 kWh/m².

For context, solar energy here swings from a low near 1.78 kWh/m² to a high of 6.45 kWh/m² in July across the year — September's 4.62 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.2Bright
45.1Bright
55.1Bright
65.0Bright
75.0Bright
85.0Bright
94.9Bright
104.8Bright
114.8Bright
124.8Bright
134.7Bright
144.6Bright
154.6Bright
164.5Bright
174.5Bright
184.4Bright
194.4Bright
204.3Bright
214.3Bright
224.3Bright
234.2Bright
244.2Bright
254.1Bright
264.1Bright
274.1Bright
284.0Bright
294.0Moderate
303.9Moderate
Planning a trip in September

Is September a good time to visit Newton?

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
5.8
Beach & pool
4th-best month of the year

September is one of the better times to visit Newton for general sightseeing.

What to pack for Newton in September

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

In September, Newton sees daytime highs around 75°F and nights near 55°F. Worth packing: light clothes, rain gear and sun protection. About 8 days see rain.

light clothesrain gearsun protection

UV index in Newton 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 Newton peaks around June 19 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 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 highHighModerateLowJun 19UV 9Dec 21UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May7Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Newton 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 Newton is worst in July — around 16 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 7 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateGoodJul 1916 µg/m³Oct 218 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb15Moderate
Mar14Moderate
Apr11Good
May12Good
Jun13Moderate
Jul16Moderate
Aug15Moderate
Sep12Good
Oct7Good
Nov9Good
Dec10Good
Location & terrain

Where is Newton?

Newton sits at 41.7°N, 93.0°W, 951 ft above sea level, in United States. The nearest listed city is Altoona, 22 mi away.

Topography around Newton

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

Within 2 miles, the terrain around Newton has only modest variations in elevation — a maximum elevation change of 200 ft around an average of 922 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 282 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 587 ft.

The land around Newton is covered by grassland (28%), cropland (26%) and trees (25%) within 2 miles, cropland (73%) within 10 miles, and cropland (68%) within 50 miles.

2 miles
200 ft
10 miles
282 ft
50 miles
587 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Altoona 22 mi · Marshalltown 25 mi · Ankeny 29 mi · Des Moines 30 mi · Johnston 34 mi · Urbandale 35 mi · West Des Moines 35 mi · Indianola 35 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 Newton (41.6997°, -93.048°, elevation 951 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).