Janesville weather in January

In January, Janesville sees average daytime highs of 28°F and overnight lows near 14°F, with 1.8 in of precipitation across 7.7 wet days and about 9.2 hours of daylight. It is the 12th-warmest and 11th-wettest month of the year here.

Day-to-day highs hold fairly steady near 28°F through the month. The sky is clear or mostly clear about 23% of the time in January, and the air most often feels dry.

Daylight stretches from about 8 h 54 min at the start of January to 9 h 42 min by month's end. Set against the rest of the year, January is Janesville's 12th-clearest and 5th-windiest month. For the whole year in context, see Janesville's year-round climate.

Daytime high: 28°; 12th warmest
Overnight low: 14°; 1st coldest
Precipitation: 1.8 in; 7.7 wet days
Daylight: 9 h 12 min; 7:30 AM – 4:41 PM
Cloud cover: 70%; 12th clearest
Wind: 8 mph; 5th windiest
Solar energy: 1.92 kWh/m²
Travel score: 0.0; 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.

← December Janesville year-round climate February →Best places to visit in January

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Temperature in January

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 28°F through the month.

A typical January day in Janesville reaches about 28°F in the afternoon and slips back to 14°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 13°F and 41°F. Set against its neighbours, January runs about 5°F cooler than December and about 4°F cooler than February.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Avg high (°F)	30	30	30	29	29	29	29	29	29	28	28	28	28	28	28	28	28	27	27	27	27	27	27	28	28	28	28	28	28	28	28
Avg low (°F)	17	17	16	16	16	15	15	15	15	15	14	14	14	14	14	13	13	13	13	13	13	13	13	13	13	13	13	14	14	14	14

	Avg high (°F)	Avg low (°F)
1	30	17
2	30	17
3	30	16
4	29	16
5	29	16
6	29	15
7	29	15
8	29	15
9	29	15
10	28	15
11	28	14
12	28	14
13	28	14
14	28	14
15	28	14
16	28	13
17	28	13
18	27	13
19	27	13
20	27	13
21	27	13
22	27	13
23	27	13
24	28	13
25	28	13
26	28	13
27	28	13
28	28	14
29	28	14
30	28	14
31	28	14

How January really feels in Janesville

Once humidity and wind are folded in, January averages 0 days that feel above 90°F and 31 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F

heat index over the day's high

Days feeling ≤ 32°F

31 feel bitter (≤ 14°F)

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

Janesville weather by month

How January compares with the rest of the year at a glance. January is the 12th-warmest and 11th-wettest month here — the current month is highlighted below.

Month	High / Low (°F)	Rainfall (inches)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	28° / 14°	1.8	7.7	6.4	9.2	0.0
Feb	32° / 17°	1.7	6.9	5.5	10.3	0.0
Mar	44° / 28°	2.4	9.4	3.5	11.6	1.0
Apr	57° / 39°	4.0	12	1.6	13.1	3.7
May	68° / 50°	3.9	12.2	0.1	14.4	5.9
Jun	78° / 60°	4.1	11.6	0	15.1	6.4
Jul	81° / 64°	3.3	10.1	0	14.8	6.5
Aug	79° / 62°	3.6	10.3	0	13.7	6.7
Sep	72° / 54°	3.3	8.8	0	12.3	6.9
Oct	59° / 42°	2.8	8.9	0.3	10.8	4.8
Nov	45° / 31°	2.2	8	2	9.6	1.1
Dec	33° / 20°	2.0	7.8	5	8.9	0.0

Cloud cover in January

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 23% of the time in January, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 11% of January, with mostly cloudy or overcast conditions the remaining 67%.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Clearer (%)	32	32	32	32	31	31	31	31	32	32	32	33	33	33	34	35	36	35	35	36	35	35	35	35	35	35	35	35	35	35	35
Cloudier (%)	68	68	68	68	69	69	69	69	68	68	68	67	67	67	66	65	64	65	65	64	65	65	65	65	65	65	65	65	65	65	65

	Clearer (%)	Cloudier (%)
1	32	68
2	32	68
3	32	68
4	32	68
5	31	69
6	31	69
7	31	69
8	31	69
9	32	68
10	32	68
11	32	68
12	33	67
13	33	67
14	33	67
15	34	66
16	35	65
17	36	64
18	35	65
19	35	65
20	36	64
21	35	65
22	35	65
23	35	65
24	35	65
25	35	65
26	35	65
27	35	65
28	35	65
29	35	65
30	35	65
31	35	65

Chance of precipitation in January

Any precipitationSnow

Janesville gets around 1.8 in of rain and snow over 7.7 wet days in January. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 25% and peaks near 27% on the wettest days, and about 6 days bring snow.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Rain chance (%)	25	25	26	26	26	27	27	27	27	27	27	27	27	27	27	26	26	26	25	24	24	23	23	23	23	23	23	22	22	22	22
Snow chance (%)	17	18	18	19	19	20	20	20	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21

	Rain chance (%)	Snow chance (%)
1	25	17
2	25	18
3	26	18
4	26	19
5	26	19
6	27	20
7	27	20
8	27	20
9	27	21
10	27	21
11	27	21
12	27	21
13	27	21
14	27	21
15	27	21
16	26	21
17	26	21
18	26	21
19	25	21
20	24	21
21	24	21
22	23	21
23	23	21
24	23	21
25	23	21
26	23	21
27	23	21
28	22	21
29	22	21
30	22	21
31	22	21

Humidity in January

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, January lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Dry (%)	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

Wind in January

Winds average 8 mph in January.

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

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Wind speed (mph)	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8
Feels	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze	light breeze

	Wind speed (mph)	Feels
1	8	light breeze
2	8	light breeze
3	8	light breeze
4	8	light breeze
5	8	light breeze
6	8	light breeze
7	8	light breeze
8	8	light breeze
9	8	light breeze
10	8	light breeze
11	8	light breeze
12	8	light breeze
13	8	light breeze
14	8	light breeze
15	8	light breeze
16	8	light breeze
17	8	light breeze
18	8	light breeze
19	8	light breeze
20	8	light breeze
21	8	light breeze
22	8	light breeze
23	8	light breeze
24	8	light breeze
25	8	light breeze
26	8	light breeze
27	8	light breeze
28	8	light breeze
29	8	light breeze
30	8	light breeze
31	8	light breeze

Sunrise & sunset in January

DaylightNight

Daylight runs from about 8 h 54 min at the start of January to 9 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 48 minutes over January. Sunrise moves from 7:32 AM to 7:20 AM, and sunset from 4:27 PM to 4:59 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Daylight (h)	8.9	8.9	8.9	9.0	9.0	9.0	9.0	9.0	9.0	9.1	9.1	9.1	9.1	9.1	9.2	9.2	9.2	9.2	9.3	9.3	9.3	9.4	9.4	9.4	9.5	9.5	9.5	9.6	9.6	9.6	9.7
Sunrise (AM)	7:32	7:32	7:32	7:32	7:32	7:32	7:32	7:32	7:32	7:32	7:31	7:31	7:31	7:30	7:30	7:30	7:29	7:29	7:28	7:28	7:27	7:27	7:26	7:25	7:25	7:24	7:23	7:22	7:21	7:20	7:20
Sunset (PM)	4:27	4:27	4:28	4:29	4:30	4:31	4:32	4:33	4:34	4:35	4:36	4:37	4:38	4:39	4:40	4:41	4:42	4:43	4:44	4:46	4:47	4:48	4:49	4:50	4:52	4:53	4:54	4:55	4:57	4:58	4:59

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	8.9	7:32	4:27
2	8.9	7:32	4:27
3	8.9	7:32	4:28
4	9.0	7:32	4:29
5	9.0	7:32	4:30
6	9.0	7:32	4:31
7	9.0	7:32	4:32
8	9.0	7:32	4:33
9	9.0	7:32	4:34
10	9.1	7:32	4:35
11	9.1	7:31	4:36
12	9.1	7:31	4:37
13	9.1	7:31	4:38
14	9.1	7:30	4:39
15	9.2	7:30	4:40
16	9.2	7:30	4:41
17	9.2	7:29	4:42
18	9.2	7:29	4:43
19	9.3	7:28	4:44
20	9.3	7:28	4:46
21	9.3	7:27	4:47
22	9.4	7:27	4:48
23	9.4	7:26	4:49
24	9.4	7:25	4:50
25	9.5	7:25	4:52
26	9.5	7:24	4:53
27	9.5	7:23	4:54
28	9.6	7:22	4:55
29	9.6	7:21	4:57
30	9.6	7:20	4:58
31	9.7	7:20	4:59

Solar energy in January

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in January, about 1.92 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 — January's 1.92 kWh/m² sits near the bottom.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Solar energy (kWh/m²)	1.6	1.6	1.6	1.7	1.7	1.7	1.7	1.7	1.8	1.8	1.8	1.8	1.8	1.9	1.9	1.9	1.9	2.0	2.0	2.0	2.0	2.1	2.1	2.1	2.2	2.2	2.2	2.3	2.3	2.3	2.4
Level	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	Solar energy (kWh/m²)	Level
1	1.6	Dim
2	1.6	Dim
3	1.6	Dim
4	1.7	Dim
5	1.7	Dim
6	1.7	Dim
7	1.7	Dim
8	1.7	Dim
9	1.8	Dim
10	1.8	Dim
11	1.8	Dim
12	1.8	Dim
13	1.8	Dim
14	1.9	Dim
15	1.9	Dim
16	1.9	Dim
17	1.9	Dim
18	2.0	Dim
19	2.0	Dim
20	2.0	Moderate
21	2.0	Moderate
22	2.1	Moderate
23	2.1	Moderate
24	2.1	Moderate
25	2.2	Moderate
26	2.2	Moderate
27	2.2	Moderate
28	2.3	Moderate
29	2.3	Moderate
30	2.3	Moderate
31	2.4	Moderate

Planning a trip in January

Is January a good time to visit Janesville?

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

0.0

Sightseeing

10th-best month of the year

0.0

Beach & pool

8th-best month of the year

January is a weaker month for outdoor sightseeing in Janesville.

What to pack for Janesville in January

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

In January, Janesville sees daytime highs around 28°F and nights near 14°F. Pack a warm layer and a heavy coat. About 8 days see rain.

a warm layera heavy coat

UV index in Janesville in January

LowModerateHighVery highExtreme

Clear-sky midday UV in January peaks around 2. 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.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	2	3	4	6	8	9	8	8	6	3	2	1
Level	Low	Moderate	Moderate	High	Very high	Very high	Very high	Very high	High	Moderate	Moderate	Low

	UV index (midday)	Level
Jan	2	Low
Feb	3	Moderate
Mar	4	Moderate
Apr	6	High
May	8	Very high
Jun	9	Very high
Jul	8	Very high
Aug	8	Very high
Sep	6	High
Oct	3	Moderate
Nov	2	Moderate
Dec	1	Low

Air quality in Janesville in January

GoodModeratePoorUnhealthyVery unhealthy

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

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
PM2.5 (µg/m³)	11	13	13	12	13	14	15	14	11	8	8	9
Level	Good	Moderate	Moderate	Good	Moderate	Moderate	Moderate	Moderate	Good	Good	Good	Good

	PM2.5 (µg/m³)	Level
Jan	11	Good
Feb	13	Moderate
Mar	13	Moderate
Apr	12	Good
May	13	Moderate
Jun	14	Moderate
Jul	15	Moderate
Aug	14	Moderate
Sep	11	Good
Oct	8	Good
Nov	8	Good
Dec	9	Good

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

artificial surfaces 37%

10 miles

348 ft

cropland 58%

50 miles

1,063 ft

cropland 56%

treesgrasslandcroplandartificial surfacesbare terrainwater

← December Janesville year-round climate February →Best places to visit in January

January 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

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).

	Avg high (°F)	Avg low (°F)
1	30	17
2	30	17
3	30	16
4	29	16
5	29	16
6	29	15
7	29	15
8	29	15
9	29	15
10	28	15
11	28	14
12	28	14
13	28	14
14	28	14
15	28	14
16	28	13
17	28	13
18	27	13
19	27	13
20	27	13
21	27	13
22	27	13
23	27	13
24	28	13
25	28	13
26	28	13
27	28	13
28	28	14
29	28	14
30	28	14
31	28	14

	Clearer (%)	Cloudier (%)
1	32	68
2	32	68
3	32	68
4	32	68
5	31	69
6	31	69
7	31	69
8	31	69
9	32	68
10	32	68
11	32	68
12	33	67
13	33	67
14	33	67
15	34	66
16	35	65
17	36	64
18	35	65
19	35	65
20	36	64
21	35	65
22	35	65
23	35	65
24	35	65
25	35	65
26	35	65
27	35	65
28	35	65
29	35	65
30	35	65
31	35	65

	Rain chance (%)	Snow chance (%)
1	25	17
2	25	18
3	26	18
4	26	19
5	26	19
6	27	20
7	27	20
8	27	20
9	27	21
10	27	21
11	27	21
12	27	21
13	27	21
14	27	21
15	27	21
16	26	21
17	26	21
18	26	21
19	25	21
20	24	21
21	24	21
22	23	21
23	23	21
24	23	21
25	23	21
26	23	21
27	23	21
28	22	21
29	22	21
30	22	21
31	22	21

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

	Avg high (°F)	Avg low (°F)
1	30	17
2	30	17
3	30	16
4	29	16
5	29	16
6	29	15
7	29	15
8	29	15
9	29	15
10	28	15
11	28	14
12	28	14
13	28	14
14	28	14
15	28	14
16	28	13
17	28	13
18	27	13
19	27	13
20	27	13
21	27	13
22	27	13
23	27	13
24	28	13
25	28	13
26	28	13
27	28	13
28	28	14
29	28	14
30	28	14
31	28	14

	Clearer (%)	Cloudier (%)
1	32	68
2	32	68
3	32	68
4	32	68
5	31	69
6	31	69
7	31	69
8	31	69
9	32	68
10	32	68
11	32	68
12	33	67
13	33	67
14	33	67
15	34	66
16	35	65
17	36	64
18	35	65
19	35	65
20	36	64
21	35	65
22	35	65
23	35	65
24	35	65
25	35	65
26	35	65
27	35	65
28	35	65
29	35	65
30	35	65
31	35	65

	Rain chance (%)	Snow chance (%)
1	25	17
2	25	18
3	26	18
4	26	19
5	26	19
6	27	20
7	27	20
8	27	20
9	27	21
10	27	21
11	27	21
12	27	21
13	27	21
14	27	21
15	27	21
16	26	21
17	26	21
18	26	21
19	25	21
20	24	21
21	24	21
22	23	21
23	23	21
24	23	21
25	23	21
26	23	21
27	23	21
28	22	21
29	22	21
30	22	21
31	22	21

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100

	Avg high (°F)	Avg low (°F)
1	30	17
2	30	17
3	30	16
4	29	16
5	29	16
6	29	15
7	29	15
8	29	15
9	29	15
10	28	15
11	28	14
12	28	14
13	28	14
14	28	14
15	28	14
16	28	13
17	28	13
18	27	13
19	27	13
20	27	13
21	27	13
22	27	13
23	27	13
24	28	13
25	28	13
26	28	13
27	28	13
28	28	14
29	28	14
30	28	14
31	28	14

	Clearer (%)	Cloudier (%)
1	32	68
2	32	68
3	32	68
4	32	68
5	31	69
6	31	69
7	31	69
8	31	69
9	32	68
10	32	68
11	32	68
12	33	67
13	33	67
14	33	67
15	34	66
16	35	65
17	36	64
18	35	65
19	35	65
20	36	64
21	35	65
22	35	65
23	35	65
24	35	65
25	35	65
26	35	65
27	35	65
28	35	65
29	35	65
30	35	65
31	35	65

	Rain chance (%)	Snow chance (%)
1	25	17
2	25	18
3	26	18
4	26	19
5	26	19
6	27	20
7	27	20
8	27	20
9	27	21
10	27	21
11	27	21
12	27	21
13	27	21
14	27	21
15	27	21
16	26	21
17	26	21
18	26	21
19	25	21
20	24	21
21	24	21
22	23	21
23	23	21
24	23	21
25	23	21
26	23	21
27	23	21
28	22	21
29	22	21
30	22	21
31	22	21

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100
31	100