Avg High
Ottawa in December
Avg Low
Rain
Daylight
9h
What to expect
Ottawa is in early winter during December, with the season well established by this point. It runs deeply cold most days, and a gentle drop-off once the sun goes down. Conditions tend to feel steady, which makes planning simple. Shorter daylight windows make plan sequencing more important.
December in context
How it compares to the rest of the year in Ottawa.
Hottest (avg)
#10 / 12
Wettest (avg)
#8 / 12
Daylight Hours
#12 / 12
Windiest (avg)
#4 / 12
Highest UV
#12 / 12
Most Humid
#1 / 12
Monthly climate breakdown
Temperature
- Daytime high
-
- Nighttime low
-
- Feels like (avg)
-
Sunshine
- Daylight hours
- 8.8 h
- UV index (max)
- 2
- Typical sun hours
- 07:34 - 16:21
Rain & Snow
- Total rain
-
- Rainy days
- 14 days
- Cloud cover (avg)
- 79%
- Snowfall
-
Humidity & Wind
- Humidity (avg)
- 79%
- Wind (avg)
-
- Wind (max gusts)
-
Daily climate explorer
Day 15 selected for December. Typical high -0.2°C and low -8.4°C.
Typical disruptions in December
Based on 30 years of historical data, these are the disruption patterns most likely to affect plans in December.
Cold High impact
Cold feels-like nights Measures: Cold feels-like nights (min <=5C). Observed about 100% of days (31.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
31.0 days / month
~100% of days
Why this matters
- Expected days 31.0 days / month
- Probability ~100% of days
- Intensity Up to ~-3°C (P95)
Cold feels-like nights are possible on ~31 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Cold High impact
Freezing nights Measures: Freezing nights (min <=0C). Observed about 91% of days (28.3 days/month) in December. Historical risk signal only, not a day-by-day forecast.
28.3 days / month
~91% of days
Why this matters
- Expected days 28.3 days / month
- Probability ~91% of days
- Intensity Up to ~-1°C (P95)
Freezing nights are possible on ~28 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cold High impact
Hard freeze nights Measures: Hard freeze nights (min <=-2C). Observed about 79% of days (24.6 days/month) in December. Historical risk signal only, not a day-by-day forecast.
24.6 days / month
~79% of days
Why this matters
- Expected days 24.6 days / month
- Probability ~79% of days
- Intensity Up to ~-3°C (P95)
Hard freeze conditions are possible on ~25 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Snow High impact
Snow days Measures: Snow days (>=0.1mm snowfall). Observed about 48% of days (14.9 days/month) in December. Historical risk signal only, not a day-by-day forecast.
14.9 days / month
~48% of days
Why this matters
- Expected days 14.9 days / month
- Probability ~48% of days
- Intensity Up to ~7.7mm (P95)
Snowfall is possible on ~15 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain High impact
Rain disruption Measures: Likely rain disruption days. Observed about 18% of days (5.5 days/month) in December. Historical risk signal only, not a day-by-day forecast.
5.5 days / month
~18% of days
Why this matters
- Expected days 5.5 days / month
- Probability ~18% of days
- Intensity Up to ~26mm (P95)
Rain disruption risk appears on ~6 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Washout risk Measures: Washout day risk. Observed about 18% of days (5.5 days/month) in December. Historical risk signal only, not a day-by-day forecast.
5.5 days / month
~18% of days
Why this matters
- Expected days 5.5 days / month
- Probability ~18% of days
- Intensity Up to ~26mm (P95)
Washout conditions are possible on ~5 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Show all disruptions (20 more)
Wind High impact
Strong gusts Measures: Strong gust days (>=60 km/h). Observed about 5% of days (1.7 days/month) in December. Historical risk signal only, not a day-by-day forecast.
1.7 days / month
~5% of days
Why this matters
- Expected days 1.7 days / month
- Probability ~5% of days
- Intensity Up to ~79km/h (P95)
Strong gusts are possible on ~2 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Wind High impact
Stormy conditions Measures: Storm-impact proxy days. Observed about 4% of days (1.2 days/month) in December. Historical risk signal only, not a day-by-day forecast.
1.2 days / month
~4% of days
Why this matters
- Expected days 1.2 days / month
- Probability ~4% of days
- Intensity Up to ~76km/h (P95)
Stormy conditions are possible on ~1 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain High impact
Washout run Measures: Multi-day washout runs. Observed about 0.9 days/month in December. Historical risk signal only, not a day-by-day forecast.
0.9 days / month
Probability unavailable
Why this matters
- Expected days 0.9 days / month
- Probability —
- Intensity Up to ~26mm (P95)
Multi-day washout runs are possible on ~1 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Very heavy rain Measures: Very heavy rain days (>=25mm). Observed about 1% of days (0.4 days/month) in December. Historical risk signal only, not a day-by-day forecast.
0.4 days / month
~1% of days
Why this matters
- Expected days 0.4 days / month
- Probability ~1% of days
- Intensity Up to ~41mm (P95)
Very heavy rain is possible on ~0 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Visibility Moderate
Fog-likely signal Measures: Fog-likely visibility proxy. Observed about 9% of days (2.9 days/month) in December. Historical risk signal only, not a day-by-day forecast.
2.9 days / month
~9% of days
Why this matters
- Expected days 2.9 days / month
- Probability ~9% of days
- Intensity Up to ~99% (P95)
Fog-likely conditions are possible on ~3 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Moderate
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 8% of days (2.5 days/month) in December. Historical risk signal only, not a day-by-day forecast.
2.5 days / month
~8% of days
Why this matters
- Expected days 2.5 days / month
- Probability ~8% of days
- Intensity Up to ~30mm (P95)
Heavy rain is possible on ~2 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cold Moderate
Cold snap run Measures: Cold snap runs (>=3 cold days). Observed about 1.3 days/month in December. Historical risk signal only, not a day-by-day forecast.
1.3 days / month
Probability unavailable
Why this matters
- Expected days 1.3 days / month
- Probability —
- Intensity Up to ~6°C (P95)
Cold snap runs are possible on ~1 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Daylight Minor
Short daylight Measures: Short daylight days (<=9h). Observed about 100% of days (31.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
31.0 days / month
~100% of days
Why this matters
- Expected days 31.0 days / month
- Probability ~100% of days
- Intensity Up to ~9.0h (P95)
Short daylight windows are possible on ~31 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cold Minor
Cold nights Measures: Cold nights (min <=5C). Observed about 100% of days (30.9 days/month) in December. Historical risk signal only, not a day-by-day forecast.
30.9 days / month
~100% of days
Why this matters
- Expected days 30.9 days / month
- Probability ~100% of days
- Intensity Up to ~1°C (P95)
Cold nights are possible on ~31 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Cold Minor
Cold days Measures: Cold days (max <=10C). Observed about 99% of days (30.5 days/month) in December. Historical risk signal only, not a day-by-day forecast.
30.5 days / month
~99% of days
Why this matters
- Expected days 30.5 days / month
- Probability ~99% of days
- Intensity Up to ~7°C (P95)
Cold daytime conditions are possible on ~31 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 83% of days (25.6 days/month) in December. Historical risk signal only, not a day-by-day forecast.
25.6 days / month
~83% of days
Why this matters
- Expected days 25.6 days / month
- Probability ~83% of days
- Intensity Up to ~100% (P95)
Cloudy skies are possible on ~26 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cloud Minor
Mostly cloudy days Measures: Mostly cloudy days (cloud cover >=80%). Observed about 61% of days (19.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
19.0 days / month
~61% of days
Why this matters
- Expected days 19.0 days / month
- Probability ~61% of days
- Intensity Up to ~100% (P95)
Mostly cloudy skies are possible on ~19 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 57% of days (17.6 days/month) in December. Historical risk signal only, not a day-by-day forecast.
17.6 days / month
~57% of days
Why this matters
- Expected days 17.6 days / month
- Probability ~57% of days
- Intensity Up to ~19mm (P95)
Measurable rain is possible on ~18 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Humidity Minor
High humidity Measures: High humidity days (RH >=80%). Observed about 52% of days (16.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
16.0 days / month
~52% of days
Why this matters
- Expected days 16.0 days / month
- Probability ~52% of days
- Intensity Up to ~97% (P95)
High humidity is possible on ~16 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Rain Minor
Rainy hours Measures: Rain-hours signal (>=3h rain). Observed about 46% of days (14.4 days/month) in December. Historical risk signal only, not a day-by-day forecast.
14.4 days / month
~46% of days
Why this matters
- Expected days 14.4 days / month
- Probability ~46% of days
- Intensity Up to ~22h (P95)
Several rainy hours are possible on ~14 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind Minor
Gusty days Measures: Gusty days (>=40 km/h). Observed about 35% of days (10.8 days/month) in December. Historical risk signal only, not a day-by-day forecast.
10.8 days / month
~35% of days
Why this matters
- Expected days 10.8 days / month
- Probability ~35% of days
- Intensity Up to ~67km/h (P95)
Gusty conditions are possible on ~11 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain Minor
Wet most of day Measures: Wet-most-of-day signal (>=6h rain). Observed about 34% of days (10.6 days/month) in December. Historical risk signal only, not a day-by-day forecast.
10.6 days / month
~34% of days
Why this matters
- Expected days 10.6 days / month
- Probability ~34% of days
- Intensity Up to ~23h (P95)
Wet-most-of-day conditions are possible on ~11 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 30% of days (9.2 days/month) in December. Historical risk signal only, not a day-by-day forecast.
9.2 days / month
~30% of days
Why this matters
- Expected days 9.2 days / month
- Probability ~30% of days
- Intensity Up to ~100% (P95)
Overcast skies are possible on ~9 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Other Minor
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data Measures: Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data. Observed about 9% of days (2.9 days/month) in December. Historical risk signal only, not a day-by-day forecast.
2.9 days / month
~9% of days
Why this matters
- Expected days 2.9 days / month
- Probability ~9% of days
- Intensity Up to ~99 (P95)
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data is possible on ~3 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Other Minor
Heavy snowfall (INACTIVE until snowfall_sum units confirmed; set threshold once units are verified) Measures: Heavy snowfall (INACTIVE until snowfall_sum units confirmed; set threshold once units are verified). Observed about 6% of days (2.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
2.0 days / month
~6% of days
Why this matters
- Expected days 2.0 days / month
- Probability ~6% of days
- Intensity Up to ~18 (P95)
Heavy snowfall (INACTIVE until snowfall_sum units confirmed; set threshold once units are verified) is possible on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Frequently asked questions
Is December a good time to visit Ottawa?
Typical December days in Ottawa reach highs of -1°C (30°F) with nights around -8°C (18°F). It usually feels cold by day and very cold after dark. Overall, December sits in the middle of the Ottawa climate range.
What are temperatures like in December?
Daytime temperatures in December typically peak near -1°C (30°F), while nights drop to around -8°C (18°F). Expect cold afternoons and very cold evenings.
How much does it rain in December?
Rainfall in December averages 84 mm (3.3 in) across roughly 14 days. Overall it is a very wet time of year, so a light rain jacket and waterproof shoes are very handy.
How many hours of daylight are there in December?
You can expect about 9 hours of daylight in December. Sunrise is typically around 07:34 and sunset near 16:21. Daylight is quite limited, and it can feel like a short-day season.
How strong is the sun in December?
UV levels are usually low (around 2), so standard sun protection is enough.
Is it windy in December?
In December, average wind speeds are around 12 km/h (7 mph), with gusts on the windiest days reaching about 53 km/h (33 mph). On the ground, it is it can feel quite windy at times, particularly when weather systems move through.