Janesville in Summer
In summer (June, July and August), Janesville sees average daytime highs around 79°F and overnight lows near 62°F, with 11.1 in of rain over about 32 wet days across the season. It is the warmest season of the year and the wettest season of the year.
Over the season highs climb from about 74°F in early June to 78°F by late August. The sky is clear or mostly clear about 33% of the time across summer, and the air most often feels comfortable.
Summer is Janesville's best season of the year to visit on our travel score. For the whole year in context, see Janesville's year-round climate.
- Avg daytime high
- 79°F
- warmest season of the year
- Avg overnight low
- 62°F
- Rainfall
- 11.1 in
- 32 wet days
- Avg wind
- 7 mph
- Travel score
- 6.5
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in Janesville in Summer
Over the season highs climb from about 74°F in early June to 78°F by late August.
A typical summer day in Janesville reaches about 79°F and drops to 62°F overnight. The warmest of the three months is July, the coolest June.
How summer really feels in Janesville
Once humidity and wind are folded in, summer brings about 0 days that feel above 90°F and 0 that feel at or below 32°F.
summer 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 the three summer months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| 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 Summer
The sky is clear or mostly clear about 33% of the time across summer.
Chance of precipitation in Summer
Janesville gets around 11.1 in of rain over 32 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 7 mph across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 54 min in early June to 13 h 06 min by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 6.0 kWh/m².
Is summer a good time to visit Janesville?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a reasonable time to visit Janesville for sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Janesville in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Janesville sees daytime highs around 79°F and nights near 62°F. Pack light clothes and sun protection. Worth having: rain gear. About 32 days see rain.
UV index in Janesville in Summer
Clear-sky midday UV across summer averages around 8 (very high — sun protection essential). 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 Summer
Average fine-particle pollution (PM2.5) through the year — so you can see where summer 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 |
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.
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.