Janesville weather in April

In April, Janesville sees average daytime highs of 57°F and overnight lows near 39°F, with 4.0 in of precipitation across 12 wet days and about 13.1 hours of daylight. It is the 7th-warmest and 2nd-wettest month of the year here.

Highs climb over the month, from about 52°F in the first days to 61°F by the end. The sky is clear or mostly clear about 22% of the time in April, and the air most often feels dry.

Daylight stretches from about 12 h 24 min at the start of April to 13 h 48 min by month's end. Set against the rest of the year, April is Janesville's 10th-clearest and 1st-windiest month. For the whole year in context, see Janesville's year-round climate.

Daytime high
57°
7th warmest
Overnight low
39°
6th coldest
Precipitation
4.0 in
12 wet days
Daylight
13 h 12 min
5:21 AM – 6:31 PM
Cloud cover
68%
10th clearest
Wind
9 mph
1st windiest
Solar energy
4.91 kWh/m²
Travel score
3.7
out of 10

Janesville is city in and county seat of Rock County, Wisconsin, United States.

Density
720/km²
people per km²
Founded
1853

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

Temperature in April

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 52°F in the first days to 61°F by the end.

A typical April day in Janesville reaches about 57°F in the afternoon and slips back to 39°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 43°F and 71°F. Set against its neighbours, April runs about 13°F warmer than March and about 11°F cooler than May.

20°40°60°80°151015202530
Avg high (°F)Avg low (°F)
15134
25234
35234
45335
55335
65335
75436
85436
95436
105537
115537
125637
135638
145638
155738
165739
175839
185840
195840
205940
215940
225941
236041
246042
256042
266142
276143
286143
296244
306244

How April really feels in Janesville

Once humidity and wind are folded in, April averages 0 days that feel above 90°F and 14 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
14
wind chill below the day's low

The story in April is cold — wind chill drags the overnight "feels like" below the raw low.

Janesville weather by month

How April compares with the rest of the year at a glance. April is the 7th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan28° / 14°1.87.76.49.20.0
Feb32° / 17°1.76.95.510.30.0
Mar44° / 28°2.49.43.511.61.0
Apr57° / 39°4.0121.613.13.7
May68° / 50°3.912.20.114.45.9
Jun78° / 60°4.111.6015.16.4
Jul81° / 64°3.310.1014.86.5
Aug79° / 62°3.610.3013.76.7
Sep72° / 54°3.38.8012.36.9
Oct59° / 42°2.88.90.310.84.8
Nov45° / 31°2.2829.61.1
Dec33° / 20°2.07.858.90.0

Cloud cover in April

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 22% of the time in April.

Beyond those clear spells, partly cloudy skies cover about 12% of April, with mostly cloudy or overcast conditions the remaining 66%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13466
23466
33466
43466
53367
63268
73367
83268
93268
103268
113367
123367
133268
143268
153367
163466
173466
183466
193565
203664
213664
223664
233664
243664
253664
263664
273664
283664
293664
303664

Chance of precipitation in April

Any precipitationSnow

Janesville gets around 4.0 in of rain and snow over 12 wet days in April. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 40% and peaks near 42% on the wettest days, and about 2 days bring snow.

0%10%20%30%40%50%151015202530
Rain chance (%)Snow chance (%)
1356
2367
3367
4377
5377
6377
7388
8388
9398
10398
11408
12408
13417
14417
15417
16416
17426
18426
19425
20424
21424
22424
23413
24413
25412
26412
27402
28401
29401
30401

Humidity in April

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, April lands in the dry band about 97% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
19910
29910
39910
49910
59910
69910
79910
89910
99721
109721
119721
129721
139721
149721
159721
169721
179721
189721
199721
209721
219721
229631
239631
249631
259541
269541
279451
289451
299361
309361

Wind in April

Winds average 9 mph in April, the windiest month of the year.

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

051015151015202530
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
79light breeze
89light breeze
99light breeze
109light breeze
119light breeze
129light 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 April

DaylightNight

Daylight runs from about 12 h 24 min at the start of April to 13 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 84 minutes over April. Sunrise moves from 5:48 AM to 5:00 AM, and sunset from 6:14 PM to 6:47 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.45:486:14
212.55:466:15
312.55:446:16
412.65:426:17
512.65:416:18
612.75:396:20
712.75:376:21
812.85:356:22
912.85:346:23
1012.95:326:24
1112.95:306:25
1213.05:286:26
1313.05:276:28
1413.15:256:29
1513.15:236:30
1613.25:216:31
1713.25:206:32
1813.35:186:33
1913.35:176:35
2013.35:156:36
2113.45:136:37
2213.45:126:38
2313.55:106:39
2413.55:096:40
2513.65:076:42
2613.65:056:43
2713.75:046:44
2813.75:026:45
2913.85:016:46
3013.85:006:47

Solar energy in April

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in April, about 4.91 kWh/m².

For context, solar energy here swings from a low near 1.59 kWh/m² to a high of 6.29 kWh/m² in June across the year — April's 4.91 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
14.4Bright
24.5Bright
34.5Bright
44.5Bright
54.6Bright
64.6Bright
74.6Bright
84.7Bright
94.7Bright
104.7Bright
114.8Bright
124.8Bright
134.8Bright
144.8Bright
154.9Bright
164.9Bright
175.0Bright
185.0Bright
195.0Bright
205.1Bright
215.1Bright
225.1Bright
235.2Bright
245.2Bright
255.2Bright
265.2Bright
275.2Bright
285.3Bright
295.3Bright
305.3Bright
Planning a trip in April

Is April a good time to visit Janesville?

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

3.7
Sightseeing
7th-best month of the year
0.2
Beach & pool
7th-best month of the year

April is a weaker month for outdoor sightseeing in Janesville.

What to pack for Janesville in April

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

In April, Janesville sees daytime highs around 57°F and nights near 39°F. Worth packing: a warm layer, rain gear and sun protection. About 12 days see rain.

a warm layerrain gearsun protection

UV index in Janesville in April

LowModerateHighVery highExtreme

Clear-sky midday UV in April 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 Janesville peaks around June 19 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 19UV 9Dec 22UV 1
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun9Very high
Jul8Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Janesville in April

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Janesville is worst in July — around 15 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (October, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateModerateGoodJul 1715 µg/m³Oct 238 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb13Moderate
Mar13Moderate
Apr12Good
May13Moderate
Jun14Moderate
Jul15Moderate
Aug14Moderate
Sep11Good
Oct8Good
Nov8Good
Dec9Good
Location & terrain

Where is Janesville?

Janesville sits at 42.7°N, 89.0°W, 837 ft above sea level, in United States. The nearest listed city is Beloit, 12 mi away.

Topography around Janesville

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

Within 2 miles, the terrain around Janesville has only modest variations in elevation — a maximum elevation change of 200 ft around an average of 833 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 348 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,063 ft.

The land around Janesville is covered by artificial surfaces (37%), trees (34%) and grassland (22%) within 2 miles, cropland (58%) within 10 miles, and cropland (56%) and trees (22%) within 50 miles.

2 miles
200 ft
10 miles
348 ft
50 miles
1,063 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
April weather nearby: Beloit 12 mi · Machesney Park 23 mi · Loves Park 25 mi · Rockford 29 mi · Fitchburg 30 mi · Belvidere 30 mi · Madison 33 mi · Sun Prairie 36 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 Janesville (42.6828°, -89.0187°, elevation 837 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).