Rosemont in Winter
In winter (December, January and February), Rosemont sees average daytime highs around 59°F and overnight lows near 42°F, with 14.4 in of rain over about 29 wet days across the season. It is the coldest season of the year and the wettest season of the year.
Over the season highs climb from about 59°F in early December to 63°F by late February. The sky is clear or mostly clear about 34% of the time across winter, and the air most often feels dry.
Winter is Rosemont's weakest season of the year to visit on our travel score. For the whole year in context, see Rosemont's year-round climate.
- Avg daytime high
- 59°F
- coldest season of the year
- Avg overnight low
- 42°F
- Rainfall
- 14.4 in
- 29 wet days
- Avg wind
- 5 mph
- Travel score
- 4.5
- weakest season of the year
- Months
- Dec · Jan · Feb
Temperature in Rosemont in Winter
Over the season highs climb from about 59°F in early December to 63°F by late February.
A typical winter day in Rosemont reaches about 59°F and drops to 42°F overnight. The warmest of the three months is February, the coolest December.
How winter really feels in Rosemont
Once humidity and wind are folded in, winter brings about 0 days that feel above 90°F and 0 that feel at or below 32°F.
winter sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
Rosemont weather by month
How the three winter months (December, January and February) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 57° / 41° | 4.9 | 9.5 | 9.6 | 4.2 |
| Feb | 62° / 43° | 4.7 | 9.6 | 10.5 | 5.2 |
| Mar | 66° / 46° | 4.1 | 9.2 | 11.7 | 6.3 |
| Apr | 72° / 50° | 1.9 | 5.8 | 13 | 7.5 |
| May | 80° / 55° | 1.1 | 4 | 14.1 | 7.7 |
| Jun | 88° / 59° | 0.2 | 1 | 14.6 | 5.9 |
| Jul | 91° / 62° | 0.0 | 0.1 | 14.4 | 4.8 |
| Aug | 91° / 61° | 0.1 | 0.2 | 13.5 | 5.0 |
| Sep | 87° / 59° | 0.1 | 0.7 | 12.3 | 6.4 |
| Oct | 78° / 53° | 1.4 | 3.2 | 11 | 8.3 |
| Nov | 65° / 45° | 2.6 | 6.6 | 9.9 | 6.5 |
| Dec | 57° / 40° | 4.8 | 9.7 | 9.4 | 4.1 |
Cloud cover in Winter
The sky is clear or mostly clear about 34% of the time across winter.
Chance of precipitation in Winter
Rosemont gets around 14.4 in of rain over 29 wet days across winter. The line is the day-by-day chance of measurable precipitation.
Humidity in Winter
Most of winter feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Winter
Winds average 5 mph across winter.
Sunrise & sunset in Winter
Daylight runs from about 9 h 30 min in early December to 11 hours by late February. The lit band spans sunrise to sunset each day.
Solar energy in Winter
Average shortwave solar energy reaching the ground each day across winter, about 2.5 kWh/m².
Hazard calendar for Rosemont
In winter, Rosemont overlaps its rainy season season. The full year is below, with each hazard's peak months called out.
Rosemont's rainy season runs November–March, when most of the year's rain falls.
Is winter a good time to visit Rosemont?
Our two travel scores rate winter for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
winter is a reasonable time to visit Rosemont for sightseeing.
What to pack for Rosemont in Winter
From winter's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In winter, Rosemont sees daytime highs around 59°F and nights near 42°F. Worth packing: a warm layer and rain gear. About 29 days see rain.
UV index in Rosemont in Winter
Clear-sky midday UV across winter averages around 3. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Rosemont peaks around June 21 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 14 at about 2 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 3 | 4 | 6 | 8 | 10 | 10 | 9 | 6 | 5 | 2 | 2 |
| Level | Moderate | Moderate | Moderate | High | Very high | Very high | Very high | Very high | High | Moderate | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Moderate |
| Feb | 3 | Moderate |
| Mar | 4 | Moderate |
| Apr | 6 | High |
| May | 8 | Very high |
| Jun | 10 | Very high |
| Jul | 10 | Very high |
| Aug | 9 | Very high |
| Sep | 6 | High |
| Oct | 5 | Moderate |
| Nov | 2 | Moderate |
| Dec | 2 | Low |
Air quality in Rosemont in Winter
Average fine-particle pollution (PM2.5) through the year — so you can see where winter falls, not just the annual average.
Air quality in Rosemont is worst in August — around 27 µg/m³ PM2.5 (moderate), about 3.6× the cleanest month (June, 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) | 15 | 14 | 15 | 12 | 9 | 8 | 11 | 27 | 23 | 17 | 19 | 14 |
| Level | Moderate | Moderate | Moderate | Good | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 15 | Moderate |
| Feb | 14 | Moderate |
| Mar | 15 | Moderate |
| Apr | 12 | Good |
| May | 9 | Good |
| Jun | 8 | Good |
| Jul | 11 | Good |
| Aug | 27 | Moderate |
| Sep | 23 | Moderate |
| Oct | 17 | Moderate |
| Nov | 19 | Moderate |
| Dec | 14 | Moderate |
Where is Rosemont?
Rosemont sits at 38.6°N, 121.4°W, 49 ft above sea level, in United States. The nearest listed city is Arden-Arcade, 3.7 mi away.
Topography around Rosemont
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Rosemont.
Within 2 miles, the terrain around Rosemont has only modest variations in elevation — a maximum elevation change of 108 ft around an average of 52 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 328 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 5,384 ft.
The land around Rosemont is covered by artificial surfaces (51%) and trees (20%) within 2 miles, artificial surfaces (43%), grassland (28%) and trees (20%) within 10 miles, and trees (34%), grassland (31%) and cropland (23%) 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 Rosemont (38.5519°, -121.3647°, elevation 49 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.