Cornwall weather in May

In May, Cornwall sees average daytime highs of 19°C and overnight lows near 8°C, with 98 mm of precipitation across 12.2 wet days and about 14.6 hours of daylight. It is the 5th-warmest and 5th-wettest month of the year here.

Highs climb over the month, from about 16°C in the first days to 21°C by the end. The sky is clear or mostly clear about 22% of the time in May, and the air most often feels dry.

Daylight stretches from about 14 hours at the start of May to 15 h 06 min by month's end. Set against the rest of the year, May is Cornwall's 5th-clearest and 8th-windiest month. For the whole year in context, see Cornwall's year-round climate.

Daytime high
19°
5th warmest
Overnight low
8th coldest
Precipitation
98 mm
12.2 wet days
Daylight
14 h 36 min
4:36 AM – 7:14 PM
Cloud cover
66%
5th clearest
Wind
11 km/h
8th windiest
Solar energy
5.53 kWh/m²
Travel score
5.6
out of 10

Cornwall is city in Ontario, Canada.

Air quality
Good
PM2.5 6 µg/m³ · 2019
Density
793/km²
people per km²
Founded
1784

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 16°C in the first days to 21°C by the end.

A typical May day in Cornwall reaches about 19°C in the afternoon and slips back to 8°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 12°C and 26°C. Set against its neighbours, May runs about 7°C warmer than April and about 5°C cooler than June.

10°20°30°151015202531
Avg high (°C)Avg low (°C)
1165
2165
3166
4176
5176
6176
7176
8187
9187
10187
11187
12187
13187
14198
15198
16198
17198
18198
19209
20209
21209
22209
23209
242010
252110
262110
272110
282110
292110
302111
312111

How May really feels in Cornwall

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

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
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.

Cornwall weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-4° / -12°7311.410.590.0
Feb-2° / -12°61108.710.10.0
Mar / -6°7611.2711.60.2
Apr12° / 10112.12.813.22.8
May19° / 9812.20.114.65.6
Jun24° / 13°10512.4015.46.3
Jul26° / 16°10012.9015.16.2
Aug25° / 15°9411.6013.96.6
Sep21° / 11°9310.5012.36.4
Oct13° / 105120.610.73.6
Nov / -1°8412.43.79.30.6
Dec-0° / -7°8212.49.38.60.0

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 22% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 16% of May, with mostly cloudy or overcast conditions the remaining 62%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13565
23664
33664
43664
53862
63862
73862
83763
93763
103862
113961
123862
133862
143961
153961
163961
173961
184060
194060
204060
214060
223961
233961
243862
253961
263763
273862
283763
293664
303664
313664

Chance of precipitation in May

Any precipitationSnow

Cornwall gets around 98 mm of rain and snow over 12.2 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 39% and peaks near 43% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%50%151015202531
Rain chance (%)Snow chance (%)
1402
2402
3391
4391
5391
6391
7381
8381
9381
10371
11371
12371
13361
14361
15361
16361
17370
18370
19370
20380
21380
22390
23390
24400
25410
26410
27420
28420
29430
30430
31430

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 87% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
196400
295410
394510
494510
594510
694510
794510
894510
993610
1093610
1193610
1292620
1392620
1492620
1592620
1691720
1790730
1890730
1988840
2086851
2184961
2284961
23821071
24811081
25791092
26781192
277612102
287612102
297513102
307313113
317214113

Wind in May

Winds average 11 km/h in May.

Across May, daily wind ranges from about 11 km/h on the calmest days to 11 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
111calm
211calm
311calm
411calm
511calm
611calm
711calm
811calm
911calm
1011calm
1111calm
1211calm
1311calm
1411calm
1511calm
1611calm
1711calm
1811calm
1911calm
2011calm
2111calm
2211calm
2311calm
2411calm
2511calm
2611calm
2711calm
2811calm
2911calm
3011calm
3111calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 14 hours at the start of May to 15 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 66 minutes over May. Sunrise moves from 4:56 AM to 4:22 AM, and sunset from 6:56 PM to 7:30 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.04:566:56
214.04:556:57
314.14:536:59
414.14:527:00
514.24:507:01
614.24:497:02
714.34:477:04
814.34:467:05
914.44:457:06
1014.44:437:07
1114.44:427:09
1214.54:417:10
1314.54:397:11
1414.64:387:12
1514.64:377:13
1614.64:367:14
1714.74:357:16
1814.74:347:17
1914.84:337:18
2014.84:327:19
2114.84:317:20
2214.94:307:21
2314.94:297:22
2414.94:287:23
2515.04:277:24
2615.04:267:25
2715.04:257:26
2815.04:247:27
2915.14:247:28
3015.14:237:29
3115.14:227:30

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.53 kWh/m².

For context, solar energy here swings from a low near 1.2 kWh/m² to a high of 5.91 kWh/m² in June across the year — May's 5.53 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.3Bright
45.3Bright
55.3Bright
65.3Bright
75.4Bright
85.4Bright
95.4Bright
105.5Bright
115.5Bright
125.5Bright
135.5Bright
145.5Bright
155.5Bright
165.6Bright
175.6Bright
185.6Bright
195.6Bright
205.6Bright
215.6Bright
225.6Bright
235.6Bright
245.6Bright
255.6Bright
265.6Bright
275.6Bright
285.6Bright
295.6Bright
305.6Bright
315.6Bright
Planning a trip in May

Is May a good time to visit Cornwall?

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

5.6
Sightseeing
5th-best month of the year
2.4
Beach & pool
5th-best month of the year

May is a reasonable time to visit Cornwall for sightseeing.

What to pack for Cornwall in May

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

In May, Cornwall sees daytime highs around 19°C and nights near 8°C. Worth packing: rain gear and sun protection. About 12 days see rain.

rain gearsun protection

UV index in Cornwall in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Cornwall peaks around July 14 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near January 10 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highModerateModerateLowJul 14UV 8Jan 10UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar3Moderate
Apr4Moderate
May6High
Jun6High
Jul8Very high
Aug4Moderate
Sep5High
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Cornwall?

Cornwall sits at 45.0°N, 74.7°W, 59 m above sea level, in Canada. The nearest listed city is Les Coteaux, 49 km away.

Topography around Cornwall

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Cornwall.

Within 3 km, the terrain around Cornwall has only modest variations in elevation — a maximum elevation change of 40 m around an average of 58 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 100 m; within 80 km, large variations in elevation — a maximum elevation change of 1,164 m.

The land around Cornwall is covered by trees (35%) and artificial surfaces (26%) within 3 km, trees (51%) within 16 km, and trees (58%) and cropland (28%) within 80 km.

3 km
40 m
16 km
100 m
80 km
1,164 m
treesgrasslandcroplandartificial surfaceswaterwetland
May weather nearby: Les Coteaux 49 km · Salaberry-de-Valleyfield 53 km · Saint-Lazare 63 km · Vaudreuil-Dorion 69 km · Clarence-Rockland 74 km · Orléans 78 km · Fallingbrook 78 km · Gloucester 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
Christian 53%none 35%Muslim 5%Hindu 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 Cornwall (45.0181°, -74.7281°, elevation 59 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. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).