Marshalltown weather in August

In August, Marshalltown sees average daytime highs of 80°F and overnight lows near 62°F, with 3.9 in of rain across 9.1 wet days and about 13.7 hours of daylight. It is the 2nd-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 80°F through the month. The sky is clear or mostly clear about 43% of the time in August, and the air most often feels muggy.

Daylight stretches from about 14 h 18 min at the start of August to 13 hours by month's end. Set against the rest of the year, August is Marshalltown's 2nd-clearest and 12th-windiest month. For the whole year in context, see Marshalltown's year-round climate.

Daytime high
80°
2nd warmest
Overnight low
62°
11th coldest
Rainfall
3.9 in
9.1 wet days
Daylight
13 h 42 min
5:24 AM – 7:07 PM
Cloud cover
49%
2nd clearest
Wind
7 mph
12th windiest
Solar energy
5.63 kWh/m²
Travel score
6.8
out of 10

Marshalltown is city and the county seat of Marshall County, Iowa, United States.

Density
552/km²
people per km²
Founded
1853

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

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 80°F through the month.

A typical August day in Marshalltown reaches about 80°F in the afternoon and slips back to 62°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 73°F and 88°F. Set against its neighbours, August runs about 2°F cooler than July and about 6°F warmer than September.

50°60°70°80°90°151015202531
Avg high (°F)Avg low (°F)
18264
28264
38164
48164
58163
68163
78163
88163
98163
108163
118163
128062
138062
148062
158062
168062
178062
188062
198062
208062
218062
228062
238062
248062
258061
268061
278061
288061
298061
308060
317960

How August really feels in Marshalltown

Once humidity and wind are folded in, August 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

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

Marshalltown weather by month

How August compares with the rest of the year at a glance. August is the 2nd-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan28° / 13°1.36.54.99.30.0
Feb33° / 16°1.56.44.710.30.0
Mar46° / 28°2.58.62.911.71.5
Apr60° / 40°4.511.5113.14.5
May70° / 51°5.313.50.114.36.0
Jun79° / 62°5.211.80156.3
Jul82° / 65°3.810.1014.76.3
Aug80° / 62°3.99.1013.76.8
Sep74° / 54°3.78.4012.37.2
Oct61° / 42°2.97.90.410.95.4
Nov46° / 29°2.16.71.69.61.5
Dec33° / 19°1.66.34.790.0

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 43% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 18% of August, with mostly cloudy or overcast conditions the remaining 39%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16139
26139
36040
46139
56040
66040
76040
85941
95941
105941
115941
125941
135941
145941
155941
166040
176040
186040
196139
206139
216139
226238
236238
246337
256436
266436
276535
286535
296535
306634
316733

Chance of precipitation in August

Any precipitation

Marshalltown gets around 3.9 in of rain over 9.1 wet days in August. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 29% and peaks near 31% on the wettest days.

0%10%20%30%40%151015202531
Rain chance (%)
129
229
329
429
529
630
730
830
931
1031
1131
1231
1331
1431
1531
1631
1731
1831
1930
2030
2130
2229
2329
2428
2528
2627
2726
2826
2926
3026
3126

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, August lands in the muggy band about 28% of days. Sticky, muggy-or-worse air turns up on roughly 40% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
17203025161
27203026161
37203026161
47203026151
58203026151
68212926151
79212927141
89212927141
910212827141
1010212827141
1111212727131
1211212728131
1311212628131
1411212628121
1512222528121
1612222529121
1712222529111
1812222530111
1912222530111
2012222530100
2112222530100
2213222530100
2313222530100
2414222530100
2515222529100
2616222428100
271722242890
281822242790
291922242690
302122232580
312323232380

Wind in August

Winds average 7 mph in August, the calmest month.

Across August, daily wind ranges from about 7 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze
318light breeze

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 h 18 min at the start of August to 13 hours by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over August. Sunrise moves from 5:09 AM to 5:40 AM, and sunset from 7:27 PM to 6:43 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.35:097:27
214.35:107:26
314.25:117:25
414.25:127:23
514.25:137:22
614.15:147:21
714.15:157:20
814.05:167:18
914.05:177:17
1014.05:187:16
1113.95:197:14
1213.95:207:13
1313.85:217:12
1413.85:227:10
1513.85:237:09
1613.75:247:07
1713.75:257:06
1813.65:267:04
1913.65:287:03
2013.55:297:01
2113.55:306:59
2213.55:316:58
2313.45:326:56
2413.45:336:55
2513.35:346:53
2613.35:356:51
2713.25:366:50
2813.25:376:48
2913.15:386:46
3013.15:396:45
3113.05:406:43

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 5.63 kWh/m².

For context, solar energy here swings from a low near 1.76 kWh/m² to a high of 6.44 kWh/m² in July across the year — August's 5.63 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
16.1Intense
26.1Intense
36.0Intense
46.0Intense
56.0Bright
65.9Bright
75.9Bright
85.9Bright
95.8Bright
105.8Bright
115.8Bright
125.7Bright
135.7Bright
145.7Bright
155.6Bright
165.6Bright
175.6Bright
185.6Bright
195.5Bright
205.5Bright
215.5Bright
225.5Bright
235.4Bright
245.4Bright
255.4Bright
265.4Bright
275.3Bright
285.3Bright
295.3Bright
305.3Bright
315.2Bright
Planning a trip in August

Is August a good time to visit Marshalltown?

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

6.8
Sightseeing
2nd-best month of the year
6.9
Beach & pool
2nd-best month of the year

August is a reasonable time to visit Marshalltown for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Marshalltown in August

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

In August, Marshalltown sees daytime highs around 80°F and nights near 62°F. Worth packing: light clothes, rain gear and sun protection. About 9 days see rain.

light clothesrain gearsun protection

UV index in Marshalltown in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Marshalltown peaks around June 18 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 18UV 9Dec 21UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May7Very high
Jun9Very high
Jul8Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Marshalltown in August

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Marshalltown 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 Marshalltown?

Marshalltown sits at 42.0°N, 92.9°W, 942 ft above sea level, in United States. The nearest listed city is Newton, 25 mi away.

Topography around Marshalltown

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

Within 2 miles, the terrain around Marshalltown has only modest variations in elevation — a maximum elevation change of 161 ft around an average of 902 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 266 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 620 ft.

The land around Marshalltown is covered by grassland (29%), artificial surfaces (29%) and trees (22%) within 2 miles, cropland (74%) within 10 miles, and cropland (80%) within 50 miles.

2 miles
161 ft
10 miles
266 ft
50 miles
620 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
August weather nearby: Newton 25 mi · Ames 37 mi · Altoona 40 mi · Cedar Falls 40 mi · Waterloo 42 mi · Ankeny 42 mi · Des Moines 48 mi · Johnston 48 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 Marshalltown (42.0494°, -92.908°, elevation 942 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).