Fall in Ottawa brings a steady shift from mild, comfortable days to crisp, chilly weather. You’ll see average highs cool from the low 70s °F in early September to the mid-30s °F by late November, with lows dropping from the mid-50s °F to the low 20s °F. This quick change makes autumn one of the most dynamic seasons in the city.
Cloud cover grows as the season goes on, and daylight hours shrink by over four hours from September to November.
Rain is pretty common in early fall, but by late season, frost and snow start taking over. The transition brings colorful foliage, damp days, and the first hints of winter.
If you visit Ottawa during this time, you’ll see how the weather shapes everything from outdoor plans to daily routines.
Crisp mornings, cooler afternoons, and the chance of early snowfall all play a part in how you experience the city.
Let’s walk through the season’s key patterns so you know what to expect.
Overview of Fall Weather in Ottawa
Fall in Ottawa brings sharp changes in temperature, daylight, and precipitation.
You can expect cooler days, shorter evenings, and a steady shift from rain to snow as the season moves along.
Cloud cover thickens, making the skies grayer compared to late summer.
Typical Fall Weather Patterns
Daily high temperatures in Ottawa drop from about 74°F (23°C) in early September to around 35°F (2°C) by late November.
Nighttime lows fall from 55°F (13°C) to near 23°F (-5°C). You’ll want warmer clothing as the weeks pass.
Rain is common in September, with averages near 2.8 inches (71 mm), but it drops to about 1.5 inches (38 mm) by November.
While rainfall fades, snowfall rises quickly. Early fall barely sees any snow, but by late November, the city often gets over 9 inches (23 cm) in just a month.
Cloud cover grows too. In early September, skies are clear or partly cloudy most of the time, but by late fall, over 60% of days are mostly cloudy or overcast.
Winds shift as well, starting from the south in September and turning more westerly by November, with speeds averaging 4–5 mph (6–9 km/h).
Transition from Summer to Winter
Ottawa’s weather moves from summer warmth to winter cold pretty fast.
By mid‑October, frost is common, and the growing season ends.
If you visit, expect crisp mornings and cooler evenings, even if daytime temperatures still feel mild.
Daylight drops off quickly.
In early September, you get over 13 hours of sunlight, but by late November, only about 9 hours remain.
Sunsets change from around 7:30 PM in September to near 4:20 PM by late November.
Humidity drops as fall goes on.
Early fall might feel a bit humid, but by November, the air turns dry and often chilly.
This dryness, mixed with colder air, makes late fall feel very different from September’s lingering warmth.
Average Temperatures in Fall
Temperatures in Ottawa drop quickly during the fall.
Early in the season feels mild, but by the end, it’s almost winter.
Daily highs and lows keep falling, and the switch from rain to snow becomes obvious as weeks go by.
September Temperature Trends
September in Ottawa can feel like late summer at first.
Average daytime highs sit near 22–24°C (72–75°F) in early September, then fall closer to 17°C (63°F) by the end.
Nights cool off fast, with lows ranging from 12°C (54°F) early on to about 7°C (45°F) later.
You’ll usually get comfortable weather, though mornings and evenings might feel chilly.
Rain is still more common than snow, and the average monthly rainfall is around 70 mm (2.8 inches).
Warm days aren’t rare, but they fade after mid-month.
By late September, you might need a jacket during the day, especially if it’s cloudy or windy.
October Temperature Changes
October cools down noticeably.
Average highs start near 14°C (57°F) at the beginning of the month and drop to about 8°C (46°F) by the end.
Nighttime lows often fall below 5°C (41°F) and can dip close to freezing in the second half of the month.
Snow might show up late in October, though rain is still more common.
The chance of mixed precipitation goes up, and frost is frequent in the mornings.
You’ll notice shorter days and cooler evenings, so outdoor activities are better earlier in the day.
A light coat is usually needed, and by late October, heavier clothing may be the way to go.
November Temperature Overview
By November, Ottawa’s weather leans hard toward winter.
Average highs fall from around 6°C (43°F) at the start of the month to close to 2°C (36°F) by the end.
Lows drop below freezing most nights, averaging -3°C to -6°C (27–21°F).
Snowfall becomes common, and the monthly average hits 20–25 cm (8–10 inches).
Rain is less frequent, but freezing rain or sleet can show up.
You’ll want to prepare for cold and damp weather, especially late in the month.
Daylight is limited, and with freezing temperatures, November really feels like the start of winter in Ottawa.
Precipitation and Humidity Levels
During fall in Ottawa, rainfall stays frequent while humidity levels shift as things cool down.
You’ll notice changes from September through November that affect outdoor comfort and travel.
Rainfall Frequency in Autumn
Rainfall in Ottawa during autumn goes up compared to the drier summer months.
September usually has the least rain, averaging about 54 mm (2.1 inches) over roughly 13 days.
By October, precipitation rises to around 78 mm (3.1 inches), making it one of the wetter months.
November keeps up with steady rainfall, though early snow often gets mixed in.
Precipitation in this month averages about 70 mm (2.7 inches), but it shifts from rain to snow as temperatures drop.
Autumn storms are usually moderate, not severe.
Rain tends to come as short, steady showers, not long downpours.
Outdoor activities are still possible, but you’ll want waterproof clothing or an umbrella.
Humidity Variations by Month
Humidity in Ottawa stays fairly high in autumn, though it changes as the season moves along.
In September, average relative humidity sits around 77–80%, which most people find comfortable with mild temperatures.
By October, humidity rises a bit as cooler air holds less moisture.
The air can feel damp, especially in the mornings and evenings.
You might see fog some days, especially near the Ottawa River.
In November, average humidity increases more, often reaching 85% or higher.
With colder temperatures, this can make the air feel raw and chilly.
If you’re heading outside, be ready for damp conditions that can feel colder than the thermometer says.
Sunshine, Daylight, and UV Index
Fall in Ottawa brings big changes in sunlight and daylight as the season goes on.
You’ll get shorter days, fewer hours of sunshine, and lower UV levels compared to summer, which can affect your outdoor plans.
Average Hours of Sunshine
Ottawa sees a steady drop in sunshine from September through November.
September still brings plenty of sunlight, averaging 6 to 7 hours per day.
By October, this falls to about 4 to 5 hours daily, thanks to more clouds and shorter days.
November is the dimmest month, with only 2 to 3 hours of sunshine per day on average.
This pattern reflects Ottawa’s northern latitude, where seasonal contrast is strong.
If you plan outdoor activities, September gives you the best shot at longer daylight, while November often feels much darker.
Daylight Duration Changes
Daylight length drops off fast in Ottawa during fall.
In early September, you get around 13 hours of daylight, which is great for long days outside.
By mid-October, daylight shortens to about 11 hours, and evenings come earlier.
November brings a sharper decline, with only 9 hours of daylight by the end of the month.
Here’s a quick look at daylight hours:
| Month | Daylight Hours (avg) |
|---|---|
| September | 12–13 hours |
| October | 10–11 hours |
| November | 8–9 hours |
This steady loss of daylight is one of the most noticeable things about fall.
You’ll need to plan sightseeing and outdoor trips earlier in the day as the season moves along.
Typical UV Index in Fall
The UV index in Ottawa drops off after summer.
In September, midday readings often reach a moderate level (3–5), so you might still want sunscreen if you’re outside.
By October, the index falls to low levels (1–3).
Sunburn risk is pretty low, especially on cloudy days.
In November, the UV index is usually at its lowest, often 1 or below, so sun protection isn’t really needed.
This drop reflects the sun’s lower angle and shorter days.
You’ll notice outdoor exposure feels less intense, but sunglasses still help with glare, especially when there’s water or early snow around.
First Signs of Snow and Frost
In Ottawa, the shift from mild fall weather to colder conditions shows up with the first measurable snowfall and the return of frost.
These signs mark the end of the growing season and the start of winter prep.
Onset of Snowfall in Autumn
Snow can show up in Ottawa as early as late October, though November is more typical.
The first snowfall is usually light and melts quickly, but it means winter is coming.
By mid to late November, snow happens more often and sticks around longer.
Average monthly snowfall in November is around 20–30 cm, while October usually gets just a few centimeters at most.
The ground might not hold snow until late November or early December, depending on how temperatures swing.
Early snow rarely causes big problems, but it does affect travel and outdoor plans.
Even a small amount can make roads slippery, so the city starts snow-clearing operations as soon as measurable snow falls.
For visitors, early snow can add a bit of charm to Ottawa’s parks and historic sites.
Still, you’ll want to be ready for colder, wetter conditions that make outdoor walking less comfy without the right clothes.
Frost Occurrence and Impact
Frost typically returns to Ottawa in early October.
On average, the first fall frost hits around October 6.
That’s the end of the frost-free growing season, which usually lasts about 158 days from late April to early October.
Frost forms when the air drops to 0°C or below, and it can damage sensitive plants.
If you garden, you need to harvest or cover crops by late September to avoid damage.
Even hardy plants might take a hit if frost comes early.
Frost means colder mornings and icy surfaces.
Car windows often need scraping, and sidewalks can get slick.
These changes tell you it’s time for warmer clothes and to prep homes and cars for freezing weather.
While frost is a regular part of fall in Ottawa, its timing can shift a bit each year depending on weather patterns.
Keeping an eye on local forecasts helps you adjust your plans and protect your outdoor activities or gardens.
Seasonal Highlights and Outdoor Activities
Crisp air, colorful trees, and mild temperatures make fall in Ottawa a season you’ll want to spend outside.
You can enjoy quiet escapes in nature or lively community gatherings that show off the city’s culture and landscape.
Fall Foliage and Scenic Views
Ottawa really shows off in autumn, especially in Gatineau Park. The park stretches across more than 360 square kilometers, with trails and lookouts scattered everywhere.
You’ll find spots like Champlain Lookout that let you gaze out over the Ottawa Valley. Those red, orange, and yellow leaves? They frame the view in a way that’s honestly hard to beat.
Want to stay in town? Try Major’s Hill Park, Dow’s Lake, or take a stroll along the Rideau Canal. These places sit right in the city and make it easy to snap a few photos without much effort.
Some folks book quick helicopter or small-plane tours for a different angle. You’ll fly over Parliament Hill, Rideau Hall, and a bunch of lakes, getting a bird’s-eye look at the colors.
If you’re not in a rush, hop on a canal cruise or grab a bike. You can wind through central Ottawa, taking in the changing trees and passing by the city’s landmarks as you go.
Popular Autumn Events in Ottawa
Fall in Ottawa means a string of lively events that mix food, culture, and a bit of outdoor adventure. Local fall fairs like the Carp Fair and Metcalfe Fair bring together agricultural displays, carnival rides, and live music.
You’ll find families wandering around, checking out Ottawa’s rural roots. These fairs have a way of making you feel like you’re part of a long-standing tradition.
Come October, Pumpkinferno at Upper Canada Village lights up the night with thousands of hand-carved, glowing pumpkins. People flock to this event—honestly, it’s hard not to be drawn in by the spectacle.
If you’re after those cozy fall flavors, try heading to ByWard Market. They pack the stalls with local produce, fresh-baked treats, and all sorts of autumn goodies.
Farms just outside Ottawa open up for apple picking and pumpkin patches. You can hop on a hayride or sip some fresh cider—sounds pretty perfect, right?
Runners or anyone who likes a challenge might want to check out the Ottawa Fall Colours Run in Cumberland Village. The crisp air and those bold, changing leaves make the route feel extra special.
You don’t have to be a pro to join in; the community vibe is welcoming, and everyone gets to soak up the scenery.