South Riding in Fall
In fall (September, October and November), South Riding sees average daytime highs around 67°F and overnight lows near 49°F, with 10.7 in of precipitation over about 25 wet days across the season. It is the 2nd-warmest season and the 2nd-wettest season.
Over the season highs ease from about 83°F in early September to 51°F by late November. The sky is clear or mostly clear about 38% of the time across fall, and the air most often feels dry.
Fall is South Riding's best season of the year to visit on our travel score. For the whole year in context, see South Riding's year-round climate.
- Avg daytime high
- 67°F
- 2nd-warmest season
- Avg overnight low
- 49°F
- Precipitation
- 10.7 in
- 25 wet days
- Avg wind
- 6 mph
- Travel score
- 5.7
- best season of the year
- Months
- Sep · Oct · Nov
Temperature in South Riding in Fall
Over the season highs ease from about 83°F in early September to 51°F by late November.
A typical fall day in South Riding reaches about 67°F and drops to 49°F overnight. The warmest of the three months is September, the coolest November.
How fall really feels in South Riding
Once humidity and wind are folded in, fall brings about 0 days that feel above 90°F and 10 that feel at or below 32°F.
The story in fall is cold — wind chill drags the overnight "feels like" below the raw low.
South Riding weather by month
How the three fall months (September, October and November) 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 | 42° / 28° | 3.0 | 8.6 | 3 | 9.6 | 0.3 |
| Feb | 45° / 29° | 2.8 | 8.1 | 3 | 10.5 | 1.1 |
| Mar | 54° / 36° | 3.8 | 10 | 2 | 11.7 | 3.3 |
| Apr | 66° / 46° | 3.4 | 10.3 | 0.1 | 13 | 5.8 |
| May | 74° / 56° | 3.8 | 11.3 | 0 | 14.1 | 6.5 |
| Jun | 83° / 65° | 3.4 | 11.2 | 0 | 14.7 | 5.5 |
| Jul | 88° / 69° | 3.9 | 11.8 | 0 | 14.4 | 4.4 |
| Aug | 85° / 68° | 3.3 | 10.4 | 0 | 13.5 | 5.1 |
| Sep | 78° / 60° | 4.4 | 9.5 | 0 | 12.3 | 6.7 |
| Oct | 67° / 49° | 3.4 | 7.8 | 0 | 11 | 6.5 |
| Nov | 55° / 38° | 3.0 | 7.6 | 0.3 | 9.9 | 3.9 |
| Dec | 46° / 32° | 3.5 | 9.1 | 2.1 | 9.3 | 1.3 |
Cloud cover in Fall
The sky is clear or mostly clear about 38% of the time across fall.
Chance of precipitation in Fall
South Riding gets around 10.7 in of rain and snow over 25 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 6 mph across fall.
Sunrise & sunset in Fall
Daylight runs from about 12 h 54 min in early September to 9 h 30 min by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 3.3 kWh/m².
Is fall a good time to visit South Riding?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a reasonable time to visit South Riding for sightseeing.
What to pack for South Riding in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, South Riding sees daytime highs around 67°F and nights near 49°F. Worth packing: light clothes, a warm layer and rain gear. About 25 days see rain.
UV index in South Riding in Fall
Clear-sky midday UV across fall averages around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in South Riding peaks around July 11 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 2 (low).
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 | 5 | 6 | 8 | 9 | 9 | 7 | 6 | 4 | 3 | 2 |
| Level | Moderate | Moderate | High | High | Very high | Very high | Very high | Very high | High | Moderate | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Moderate |
| Feb | 3 | Moderate |
| Mar | 5 | High |
| Apr | 6 | High |
| May | 8 | Very high |
| Jun | 9 | Very high |
| Jul | 9 | Very high |
| Aug | 7 | Very high |
| Sep | 6 | High |
| Oct | 4 | Moderate |
| Nov | 3 | Moderate |
| Dec | 2 | Low |
Air quality in South Riding in Fall
Average fine-particle pollution (PM2.5) through the year — so you can see where fall falls, not just the annual average.
Air quality in South Riding is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (November, 9 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 | 12 | 13 | 13 | 15 | 16 | 17 | 15 | 12 | 9 | 9 | 10 |
| Level | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 11 | Good |
| Feb | 12 | Moderate |
| Mar | 13 | Moderate |
| Apr | 13 | Moderate |
| May | 15 | Moderate |
| Jun | 16 | Moderate |
| Jul | 17 | Moderate |
| Aug | 15 | Moderate |
| Sep | 12 | Moderate |
| Oct | 9 | Good |
| Nov | 9 | Good |
| Dec | 10 | Good |
Where is South Riding?
South Riding sits at 38.9°N, 77.5°W, 322 ft above sea level, in United States. The nearest listed city is Chantilly, 4.3 mi away.
Topography around South Riding
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of South Riding.
Within 2 miles, the terrain around South Riding has only modest variations in elevation — a maximum elevation change of 361 ft around an average of 318 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,411 ft; within 50 miles, large variations in elevation — a maximum elevation change of 3,812 ft.
The land around South Riding is covered by trees (56%) and artificial surfaces (22%) within 2 miles, trees (61%) and grassland (20%) within 10 miles, and trees (67%) 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 South Riding (38.9209°, -77.5039°, elevation 322 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.