Janesville weather in May

In May, Janesville sees average daytime highs of 68°F and overnight lows near 50°F, with 3.9 in of precipitation across 12.2 wet days and about 14.4 hours of daylight. It is the 5th-warmest and 3rd-wettest month of the year here.

Highs climb over the month, from about 63°F in the first days to 73°F by the end. The sky is clear or mostly clear about 24% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 48 min at the start of May to 14 h 54 min by month's end. Set against the rest of the year, May is Janesville's 6th-clearest and 8th-windiest month. For the whole year in context, see Janesville's year-round climate.

Daytime high
68°
5th warmest
Overnight low
50°
8th coldest
Precipitation
3.9 in
12.2 wet days
Daylight
14 h 24 min
4:39 AM – 7:05 PM
Cloud cover
65%
6th clearest
Wind
8 mph
8th windiest
Solar energy
5.71 kWh/m²
Travel score
5.9
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 May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 63°F in the first days to 73°F by the end.

A typical May day in Janesville reaches about 68°F in the afternoon and slips back to 50°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 56°F and 81°F. Set against its neighbours, May runs about 11°F warmer than April and about 10°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
16344
26345
36345
46446
56446
66546
76547
86547
96647
106648
116648
126748
136749
146749
156849
166849
176950
186950
196951
207051
217051
227052
237152
247152
257153
267253
277253
287354
297354
307355
317355

How May really feels in Janesville

Once humidity and wind are folded in, May 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

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

Janesville weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 3rd-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 May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 24% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 61%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13664
23664
33763
43664
53763
63763
73763
83862
93862
103862
113862
123961
133961
143961
153961
163961
173961
183961
193961
203961
213961
223961
234060
244060
254060
264159
274258
284258
294258
304357
314456

Chance of precipitation in May

Any precipitation

Janesville gets around 3.9 in of rain and snow over 12.2 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 39% and peaks near 41% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%50%151015202531
Rain chance (%)
139
240
340
440
540
640
740
840
941
1041
1140
1240
1340
1440
1540
1639
1739
1839
1939
2039
2139
2238
2338
2438
2538
2639
2739
2839
2939
3039
3139

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the dry band about 79% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
192710
291720
390820
490820
589830
688930
787940
885951
985951
1085951
1184961
1284961
1383971
1483971
1582972
16801082
17801082
18791083
19781084
20761194
21751195
22741295
237212106
247113106
256914107
266914107
276715117
286616117
296516118
306317128
316218128

Wind in May

Winds average 8 mph in May.

Across May, 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.

051015151015202531
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
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
307light breeze
317calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 48 min at the start of May to 14 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 66 minutes over May. Sunrise moves from 4:58 AM to 4:27 AM, and sunset from 6:48 PM to 7:20 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.84:586:48
213.94:576:50
313.94:556:51
414.04:546:52
514.04:536:53
614.04:516:54
714.14:506:55
814.14:496:56
914.24:476:58
1014.24:466:59
1114.24:457:00
1214.34:447:01
1314.34:437:02
1414.44:427:03
1514.44:417:04
1614.44:397:05
1714.54:387:06
1814.54:377:07
1914.54:367:08
2014.64:367:09
2114.64:357:10
2214.64:347:11
2314.74:337:12
2414.74:327:13
2514.74:317:14
2614.74:317:15
2714.84:307:16
2814.84:297:17
2914.84:297:18
3014.84:287:19
3114.94:277:20

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.71 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 — May's 5.71 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.3Bright
45.4Bright
55.4Bright
65.4Bright
75.4Bright
85.5Bright
95.5Bright
105.5Bright
115.6Bright
125.6Bright
135.6Bright
145.7Bright
155.7Bright
165.7Bright
175.8Bright
185.8Bright
195.8Bright
205.8Bright
215.9Bright
225.9Bright
235.9Bright
245.9Bright
256.0Bright
266.0Bright
276.0Bright
286.0Intense
296.0Intense
306.0Intense
316.0Intense
Planning a trip in May

Is May a good time to visit Janesville?

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

5.9
Sightseeing
5th-best month of the year
3.2
Beach & pool
5th-best month of the year

May is a reasonable time to visit Janesville for sightseeing.

What to pack for Janesville in May

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

In May, Janesville sees daytime highs around 68°F and nights near 50°F. Worth packing: rain gear and sun protection. About 12 days see rain.

rain gearsun protection

UV index in Janesville in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May 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 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 May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May 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
May 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).