Avg High
Ottawa in May
Avg Low
Rain
Daylight
15h
What to expect
May in Ottawa is late spring, a shoulder-season window, so you can get a bit of variety across the month. The month is mostly mild for steady exploring, with a noticeable cool-down after sunset. Most days feel close to what the averages suggest, with straightforward pacing. There is plenty of daylight to stretch outdoor time.
May in context
How it compares to the rest of the year in Ottawa.
Hottest (avg)
#5 / 12
Wettest (avg)
#7 / 12
Daylight Hours
#3 / 12
Windiest (avg)
#8 / 12
Highest UV
#3 / 12
Most Humid
#11 / 12
Monthly climate breakdown
Temperature
- Daytime high
-
- Nighttime low
-
- Feels like (avg)
-
Sunshine
- Daylight hours
- 14.9 h
- UV index (max)
- 7
- Typical sun hours
- 04:31 - 19:26
Rain & Snow
- Total rain
-
- Rainy days
- 14 days
- Cloud cover (avg)
- 62%
- Snowfall
-
Humidity & Wind
- Humidity (avg)
- 66%
- Wind (avg)
-
- Wind (max gusts)
-
Daily climate explorer
Day 15 selected for May. Typical high 17.8°C and low 7.4°C.
Typical disruptions in May
Based on 30 years of historical data, these are the disruption patterns most likely to affect plans in May.
Cold High impact
Cold feels-like nights Measures: Cold feels-like nights (min <=5C). Observed about 54% of days (16.8 days/month) in May. Historical risk signal only, not a day-by-day forecast.
16.8 days / month
~54% of days
Why this matters
- Expected days 16.8 days / month
- Probability ~54% of days
- Intensity Up to ~5°C (P95)
Cold feels-like nights are possible on ~17 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Rain High impact
Rain disruption Measures: Likely rain disruption days. Observed about 19% of days (5.8 days/month) in May. Historical risk signal only, not a day-by-day forecast.
5.8 days / month
~19% of days
Why this matters
- Expected days 5.8 days / month
- Probability ~19% of days
- Intensity Up to ~25mm (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 May. 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 ~25mm (P95)
Washout conditions are possible on ~6 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 9% of days (2.9 days/month) in May. 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 ~33mm (P95)
Heavy rain is possible on ~3 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind High impact
Strong gusts Measures: Strong gust days (>=60 km/h). Observed about 4% of days (1.3 days/month) in May. Historical risk signal only, not a day-by-day forecast.
1.3 days / month
~4% of days
Why this matters
- Expected days 1.3 days / month
- Probability ~4% of days
- Intensity Up to ~86km/h (P95)
Strong gusts are possible on ~1 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 3% of days (0.9 days/month) in May. Historical risk signal only, not a day-by-day forecast.
0.9 days / month
~3% of days
Why this matters
- Expected days 0.9 days / month
- Probability ~3% of days
- Intensity Up to ~77km/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.
Show all disruptions (20 more)
Rain High impact
Washout run Measures: Multi-day washout runs. Observed about 1.1 days/month in May. Historical risk signal only, not a day-by-day forecast.
1.1 days / month
Probability unavailable
Why this matters
- Expected days 1.1 days / month
- Probability —
- Intensity Up to ~24mm (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 (0.3 days/month) in May. Historical risk signal only, not a day-by-day forecast.
0.3 days / month
~1% of days
Why this matters
- Expected days 0.3 days / month
- Probability ~1% of days
- Intensity Up to ~50mm (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 4% of days (1.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
1.4 days / month
~4% of days
Why this matters
- Expected days 1.4 days / month
- Probability ~4% of days
- Intensity Up to ~99% (P95)
Fog-likely conditions are possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Moderate
Hot feels-like days Measures: Hot feels-like days (>=32C). Observed about 1% of days (0.4 days/month) in May. 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 ~36°C (P95)
Feels-like heat >=32C is possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 57% of days (17.6 days/month) in May. 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 ~100% (P95)
Cloudy skies are possible on ~18 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 51% of days (15.7 days/month) in May. Historical risk signal only, not a day-by-day forecast.
15.7 days / month
~51% of days
Why this matters
- Expected days 15.7 days / month
- Probability ~51% of days
- Intensity Up to ~20mm (P95)
Measurable rain is possible on ~16 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Wind Minor
Gusty days Measures: Gusty days (>=40 km/h). Observed about 40% of days (12.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
12.4 days / month
~40% of days
Why this matters
- Expected days 12.4 days / month
- Probability ~40% of days
- Intensity Up to ~63km/h (P95)
Gusty conditions are possible on ~12 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain Minor
Rainy hours Measures: Rain-hours signal (>=3h rain). Observed about 39% of days (12.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
12.1 days / month
~39% of days
Why this matters
- Expected days 12.1 days / month
- Probability ~39% of days
- Intensity Up to ~19h (P95)
Several rainy hours are possible on ~12 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cloud Minor
Mostly cloudy days Measures: Mostly cloudy days (cloud cover >=80%). Observed about 33% of days (10.3 days/month) in May. Historical risk signal only, not a day-by-day forecast.
10.3 days / month
~33% of days
Why this matters
- Expected days 10.3 days / month
- Probability ~33% of days
- Intensity Up to ~100% (P95)
Mostly cloudy skies are possible on ~10 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 29% of days (8.9 days/month) in May. Historical risk signal only, not a day-by-day forecast.
8.9 days / month
~29% of days
Why this matters
- Expected days 8.9 days / month
- Probability ~29% of days
- Intensity Up to ~5°C (P95)
Cold nights are possible on ~9 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Rain Minor
Wet most of day Measures: Wet-most-of-day signal (>=6h rain). Observed about 27% of days (8.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
8.5 days / month
~27% of days
Why this matters
- Expected days 8.5 days / month
- Probability ~27% of days
- Intensity Up to ~20h (P95)
Wet-most-of-day conditions are possible on ~8 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Humidity Minor
High humidity Measures: High humidity days (RH >=80%). Observed about 19% of days (5.7 days/month) in May. Historical risk signal only, not a day-by-day forecast.
5.7 days / month
~19% of days
Why this matters
- Expected days 5.7 days / month
- Probability ~19% of days
- Intensity Up to ~96% (P95)
High humidity is possible on ~6 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 16% of days (5.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
5.1 days / month
~16% of days
Why this matters
- Expected days 5.1 days / month
- Probability ~16% of days
- Intensity Up to ~100% (P95)
Overcast skies are possible on ~5 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cold Minor
Cold days Measures: Cold days (max <=10C). Observed about 5% of days (1.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
1.5 days / month
~5% of days
Why this matters
- Expected days 1.5 days / month
- Probability ~5% of days
- Intensity Up to ~10°C (P95)
Cold daytime conditions are possible on ~2 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
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 4% of days (1.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
1.4 days / month
~4% of days
Why this matters
- Expected days 1.4 days / month
- Probability ~4% 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 ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Hot days Measures: Hot days (>=30C). Observed about 2% of days (0.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
0.5 days / month
~2% of days
Why this matters
- Expected days 0.5 days / month
- Probability ~2% of days
- Intensity Up to ~34°C (P95)
Hot days are possible on ~1 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Snow Minor
Snow days Measures: Snow days (>=0.1mm snowfall). Observed about 2% of days (0.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
0.5 days / month
~2% of days
Why this matters
- Expected days 0.5 days / month
- Probability ~2% of days
- Intensity Up to ~4.3mm (P95)
Snowfall is possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cold Minor
Freezing nights Measures: Freezing nights (min <=0C). Observed about 1% of days (0.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
0.5 days / month
~1% of days
Why this matters
- Expected days 0.5 days / month
- Probability ~1% of days
- Intensity Up to ~-0°C (P95)
Freezing nights are possible on ~0 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Humidity Minor
Humid days Measures: Humid days (dew point >=18C). Observed about 1% of days (0.2 days/month) in May. Historical risk signal only, not a day-by-day forecast.
0.2 days / month
~1% of days
Why this matters
- Expected days 0.2 days / month
- Probability ~1% of days
- Intensity Up to ~20°C (P95)
Humid conditions are possible on ~0 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Cold Minor
Cold snap run Measures: Cold snap runs (>=3 cold days). Observed about 0.1 days/month in May. Historical risk signal only, not a day-by-day forecast.
0.1 days / month
Probability unavailable
Why this matters
- Expected days 0.1 days / month
- Probability —
- Intensity Up to ~9°C (P95)
Cold snap runs are possible on ~0 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Frequently asked questions
Is May a good time to visit Ottawa?
Typical May days in Ottawa reach highs of 19°C (66°F) with nights around 8°C (46°F). It usually feels mild by day and cold after dark. Overall, May sits in the middle of the Ottawa climate range.
What are temperatures like in May?
In May, you can usually expect highs of 19°C (66°F) and lows near 8°C (46°F). That means mild days and cold nights, so pack layers you can add or remove.
How much does it rain in May?
Rainfall in May averages 88 mm (3.5 in) across roughly 14 days. Overall it is a quite rainy time of year, so a light rain jacket and waterproof shoes are very handy.
How many hours of daylight are there in May?
You can expect about 15 hours of daylight in May. Sunrise is typically around 04:31 and sunset near 19:26. You get long days with comfortable amounts of daylight.
How strong is the sun in May?
UV levels are often high (around 7). Regular sunscreen and a hat are recommended.
Is it windy in May?
In May, average wind speeds are around 11 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.