Ottawa weather in May

In May, Ottawa sees average daytime highs of 71°F and overnight lows near 52°F, with 4.7 in of rain across 13 wet days and about 14.3 hours of daylight. It is the 5th-warmest and 1st-wettest month of the year here.

Highs climb over the month, from about 67°F in the first days to 76°F by the end. The sky is clear or mostly clear about 25% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 48 min at the start of May to 14 h 42 min by month's end. Set against the rest of the year, May is Ottawa's 7th-clearest and 8th-windiest month. For the whole year in context, see Ottawa's year-round climate.

Daytime high
71°
5th warmest
Overnight low
52°
8th coldest
Rainfall
4.7 in
13 wet days
Daylight
14 h 18 min
4:42 AM – 7:01 PM
Cloud cover
64%
7th clearest
Wind
9 mph
8th windiest
Solar energy
5.71 kWh/m²
Travel score
6.1
out of 10

Ottawa is city in Illinois, United States.

Density
553/km²
people per km²
Founded
1853

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 67°F in the first days to 76°F by the end.

A typical May day in Ottawa reaches about 71°F in the afternoon and slips back to 52°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 59°F and 84°F. Set against its neighbours, May runs about 10°F warmer than April and about 9°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
16647
26747
36748
46748
56849
66849
76949
86950
96950
107050
117051
127051
137151
147151
157152
167152
177252
187253
197253
207353
217354
227354
237454
247455
257455
267556
277556
287556
297657
307657
317657

How May really feels in Ottawa

Once humidity and wind are folded in, May averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Ottawa weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan32° / 18°2.28.25.49.40.0
Feb37° / 21°2.07.24.210.30.0
Mar49° / 31°2.89.92.411.71.9
Apr61° / 41°4.311.90.613.14.8
May71° / 52°4.713014.36.1
Jun80° / 62°4.411.7014.96.2
Jul83° / 66°3.811.3014.75.7
Aug82° / 64°3.59.7013.76.6
Sep76° / 56°3.18.4012.37.1
Oct63° / 44°3.190.110.95.7
Nov49° / 33°2.78.61.19.72.1
Dec37° / 23°2.28.13.79.10.0

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 25% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 60%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13862
23862
33763
43664
53763
63763
73862
83862
93862
103862
113961
124060
134060
144060
154060
164159
174159
184159
194159
204258
214258
224258
234357
244357
254258
264258
274357
284357
294357
304357
314456

Chance of precipitation in May

Any precipitation

Ottawa gets around 4.7 in of rain over 13 wet days in May, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 42% and peaks near 43% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
142
242
342
442
542
642
742
842
942
1042
1142
1242
1342
1442
1543
1643
1743
1843
1943
2043
2143
2243
2342
2442
2542
2642
2742
2842
2942
3041
3141

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

Most of May feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, May lands in the dry band about 69% of days. Sticky, muggy-or-worse air turns up on roughly 6% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
188921
2861031
3851131
4831142
5821242
6821242
7791353
8791353
9771463
10761464
11751474
12741574
13721585
14721585
15711595
16701695
176816106
186816106
196616117
206516127
216316138
226316138
236017149
245917159
2558171510
2656181610
2755181611
2854181711
2952191712
3052191712
3150201713

Wind in May

Winds average 9 mph in May.

Across May, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
79light breeze
89light breeze
99light breeze
109light breeze
119light breeze
129light breeze
139light breeze
149light breeze
159light breeze
169light breeze
179light breeze
189light breeze
199light breeze
209light breeze
219light breeze
229light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze
318light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 48 min at the start of May to 14 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 54 minutes over May. Sunrise moves from 5:00 AM to 4:31 AM, and sunset from 6:45 PM to 7:15 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.85:006:45
213.84:596:46
313.84:576:47
413.94:566:48
513.94:556:50
614.04:536:51
714.04:526:52
814.04:516:53
914.14:506:54
1014.14:496:55
1114.14:476:56
1214.24:466:57
1314.24:456:58
1414.24:446:59
1514.34:437:00
1614.34:427:01
1714.34:417:02
1814.44:407:03
1914.44:397:04
2014.44:387:05
2114.54:387:06
2214.54:377:07
2314.54:367:08
2414.64:357:09
2514.64:347:10
2614.64:347:11
2714.64:337:11
2814.74:327:12
2914.74:327:13
3014.74:317:14
3114.74:317:15

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.71 kWh/m².

For context, solar energy here swings from a low near 1.72 kWh/m² to a high of 6.31 kWh/m² in June across the year — May's 5.71 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.3Bright
45.4Bright
55.4Bright
65.4Bright
75.5Bright
85.5Bright
95.5Bright
105.5Bright
115.6Bright
125.6Bright
135.6Bright
145.7Bright
155.7Bright
165.7Bright
175.8Bright
185.8Bright
195.8Bright
205.8Bright
215.8Bright
225.9Bright
235.9Bright
245.9Bright
255.9Bright
265.9Bright
275.9Bright
286.0Bright
296.0Bright
306.0Bright
316.0Intense
Planning a trip in May

Is May a good time to visit Ottawa?

Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

6.1
Sightseeing
4th-best month of the year
4.2
Beach & pool
5th-best month of the year

May is a reasonable time to visit Ottawa for sightseeing.

What to pack for Ottawa in May

From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In May, Ottawa sees daytime highs around 71°F and nights near 52°F. Worth packing: rain gear and sun protection. About 13 days see rain.

rain gearsun protection

UV index in Ottawa in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Ottawa peaks around June 20 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 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJun 20UV 9Dec 19UV 2
UV index (midday)Level
Jan2Moderate
Feb3Moderate
Mar5Moderate
Apr6High
May7Very high
Jun9Very high
Jul8Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Ottawa in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in Ottawa is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (October, 9 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodJul 1917 µg/m³Oct 229 µg/m³
PM2.5 (µg/m³)Level
Jan12Good
Feb14Moderate
Mar14Moderate
Apr13Moderate
May14Moderate
Jun15Moderate
Jul17Moderate
Aug16Moderate
Sep12Moderate
Oct9Good
Nov9Good
Dec10Good
Location & terrain

Where is Ottawa?

Ottawa sits at 41.3°N, 88.8°W, 482 ft above sea level, in United States. The nearest listed city is Yorkville, 29 mi away.

Topography around Ottawa

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Ottawa.

Within 2 miles, the terrain around Ottawa has only modest variations in elevation — a maximum elevation change of 295 ft around an average of 531 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 417 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 692 ft.

The land around Ottawa is covered by trees (36%) and artificial surfaces (24%) within 2 miles, cropland (69%) within 10 miles, and cropland (78%) within 50 miles.

2 miles
295 ft
10 miles
417 ft
50 miles
692 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Yorkville 29 mi · Oswego 34 mi · Shorewood 35 mi · Montgomery 37 mi · Plainfield 39 mi · Aurora 39 mi · DeKalb 40 mi · Crest Hill 41 mi

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
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

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 Ottawa (41.3456°, -88.8426°, elevation 482 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. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).