Alliston in Fall
In fall (September, October and November), Alliston sees average daytime highs around 13°C and overnight lows near 5°C, with 211 mm of precipitation over about 32 wet days across the season. It is the 2nd-warmest season and the 2nd-wettest season.
Over the season highs ease from about 23°C in early September to 3°C by late November. The sky is clear or mostly clear about 20% of the time across fall, and the air most often feels dry.
Fall is Alliston's 2nd-best season to visit on our travel score. For the whole year in context, see Alliston's year-round climate.
- Avg daytime high
- 13°C
- 2nd-warmest season
- Avg overnight low
- 5°C
- Precipitation
- 211 mm
- 32 wet days
- Avg wind
- 12 km/h
- Travel score
- 3.6
- 2nd-best season
- Months
- Sep · Oct · Nov
Temperature in Alliston in Fall
Over the season highs ease from about 23°C in early September to 3°C by late November.
A typical fall day in Alliston reaches about 13°C and drops to 5°C overnight. The warmest of the three months is September, the coolest November.
How fall really feels in Alliston
Once humidity and wind are folded in, fall brings about 0 days that feel above 32°C and 38 that feel at or below 0°C.
The story in fall is cold — wind chill drags the overnight "feels like" below the raw low.
Alliston 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 (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | -3° / -11° | 56 | 10.4 | 10.2 | 9.1 | 0.0 |
| Feb | -2° / -11° | 46 | 8.4 | 7.6 | 10.2 | 0.0 |
| Mar | 4° / -5° | 54 | 10.1 | 6.1 | 11.6 | 0.2 |
| Apr | 11° / 1° | 74 | 10.8 | 2.7 | 13.2 | 2.8 |
| May | 18° / 7° | 80 | 10.7 | 0 | 14.5 | 5.7 |
| Jun | 23° / 13° | 83 | 10.9 | 0 | 15.2 | 6.7 |
| Jul | 26° / 15° | 75 | 10.6 | 0 | 15 | 6.7 |
| Aug | 25° / 14° | 76 | 9.8 | 0 | 13.8 | 7.0 |
| Sep | 21° / 10° | 71 | 9.7 | 0 | 12.3 | 6.5 |
| Oct | 13° / 5° | 73 | 11.2 | 0.4 | 10.8 | 3.6 |
| Nov | 6° / -1° | 67 | 10.7 | 4.1 | 9.4 | 0.6 |
| Dec | 0° / -7° | 57 | 10.9 | 9 | 8.7 | 0.0 |
Cloud cover in Fall
The sky is clear or mostly clear about 20% of the time across fall.
Chance of precipitation in Fall
Alliston gets around 211 mm of rain and snow over 32 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 12 km/h across fall.
Sunrise & sunset in Fall
Daylight runs from about 13 h 06 min in early September to 9 hours 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 2.7 kWh/m².
Is fall a good time to visit Alliston?
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 weaker month for outdoor sightseeing in Alliston.
What to pack for Alliston in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, Alliston sees daytime highs around 13°C and nights near 5°C. Pack a warm layer. Worth having: a heavy coat and rain gear. About 32 days see rain.
Sea temperature near Alliston in Fall
The nearest coast averages about 14°C across fall — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 57 km away) is warmest in August at about 21°C and coldest in March near 1°C.
It's comfortable for a long swim from Aug 9 to Aug 24 — about 0.5 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 3 | 2 | 1 | 2 | 5 | 11 | 19 | 21 | 19 | 13 | 9 | 6 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Cool | Refreshing | Cool | Bracing | Bracing | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 3 | Bracing |
| Feb | 2 | Bracing |
| Mar | 1 | Bracing |
| Apr | 2 | Bracing |
| May | 5 | Bracing |
| Jun | 11 | Bracing |
| Jul | 19 | Cool |
| Aug | 21 | Refreshing |
| Sep | 19 | Cool |
| Oct | 13 | Bracing |
| Nov | 9 | Bracing |
| Dec | 6 | Bracing |
UV index in Alliston in Fall
Clear-sky midday UV across fall averages around 3 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Alliston peaks around June 23 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 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) | 1 | 2 | 4 | 5 | 6 | 8 | 8 | 7 | 5 | 3 | 2 | 1 |
| Level | Low | Low | Moderate | High | High | Very high | Very high | High | High | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 2 | Low |
| Mar | 4 | Moderate |
| Apr | 5 | High |
| May | 6 | High |
| Jun | 8 | Very high |
| Jul | 8 | Very high |
| Aug | 7 | High |
| Sep | 5 | High |
| Oct | 3 | Moderate |
| Nov | 2 | Low |
| Dec | 1 | Low |
Air quality in Alliston 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 Alliston is worst in May — around 19 µg/m³ PM2.5 (moderate), about 2.1× 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 | 14 | 16 | 17 | 19 | 18 | 18 | 16 | 14 | 10 | 9 | 9 |
| Level | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 11 | Good |
| Feb | 14 | Moderate |
| Mar | 16 | Moderate |
| Apr | 17 | Moderate |
| May | 19 | Moderate |
| Jun | 18 | Moderate |
| Jul | 18 | Moderate |
| Aug | 16 | Moderate |
| Sep | 14 | Moderate |
| Oct | 10 | Good |
| Nov | 9 | Good |
| Dec | 9 | Good |
Where is Alliston?
Alliston sits at 44.2°N, 79.9°W, 223 m above sea level, in Canada. The nearest listed city is Innisfil, 24 km away.
Topography around Alliston
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Alliston.
Within 3 km, the terrain around Alliston has only modest variations in elevation — a maximum elevation change of 71 m around an average of 227 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 266 m; within 80 km, significant variations in elevation — a maximum elevation change of 471 m.
The land around Alliston is covered by cropland (37%), grassland (24%) and trees (20%) within 3 km, cropland (42%), trees (35%) and grassland (21%) within 16 km, and trees (37%) and cropland (29%) within 80 km.
Canada travel facts
- Travel advisory
- Level 1
- Exercise Normal Precautions
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 83% of US
- price level, 2025
- GDP per capita
- $55,698
- 2025
- Happiness
- 6.7 / 10
- World Happiness, 2025
- Safe drinking water
- 97%
- of population, 2024
- Homicide rate
- 2
- per 100k, 2023
- Road deaths
- 5.3
- 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 Alliston (44.1501°, -79.8663°, elevation 223 m), 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.