Ajax weather in May

In May, Ajax sees average daytime highs of 12°C and overnight lows near 8°C, with 78 mm of rain across 10.1 wet days and about 14.5 hours of daylight. It is the 6th-warmest and 7th-wettest month of the year here.

Highs climb over the month, from about 9°C in the first days to 14°C by the end. The sky is clear or mostly clear about 28% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 54 min at the start of May to 15 hours by month's end. Set against the rest of the year, May is Ajax's 5th-clearest and 9th-windiest month. For the whole year in context, see Ajax's year-round climate.

Daytime high
12°
6th warmest
Overnight low
7th coldest
Rainfall
78 mm
10.1 wet days
Daylight
14 h 30 min
4:56 AM – 7:28 PM
Cloud cover
61%
5th clearest
Wind
16 km/h
9th windiest
Solar energy
5.93 kWh/m²
Travel score
3.0
out of 10

Ajax is town in Durham Region, Ontario, Canada.

Density
1,786/km²
people per km²

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 9°C in the first days to 14°C by the end.

A typical May day in Ajax reaches about 12°C in the afternoon and slips back to 8°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 8°C and 15°C. Set against its neighbours, May runs about 5°C warmer than April and about 6°C cooler than June.

10°15°20°151015202531
Avg high (°C)Avg low (°C)
195
295
396
496
596
6106
7106
8106
9107
10107
11107
12117
13117
14117
15118
16118
17128
18128
19128
20129
21129
22139
23139
24139
251310
261410
271410
281410
291411
301411
311511

How May really feels in Ajax

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.

Ajax weather by month

How May compares with the rest of the year at a glance. May is the 6th-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-1° / -6°8612.59.79.10.0
Feb-1° / -7°6196.910.20.0
Mar / -3°7010.14.711.60.0
Apr / 96111.613.20.7
May12° / 7810.1014.53.0
Jun18° / 14°769.7015.25.7
Jul23° / 19°678.9014.97.0
Aug23° / 19°678.8013.87.2
Sep20° / 16°859.1012.36.5
Oct14° / 10°9512.10.110.83.8
Nov / 9211.42.29.51.0
Dec / -2°8712.66.88.80.0

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 28% 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 56%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14456
24357
34456
44456
54456
64357
74357
84357
94456
104555
114555
124456
134456
144555
154555
164456
174555
184555
194456
204456
214456
224456
234456
244456
254555
264555
274555
284555
294456
304456
314555

Chance of precipitation in May

Any precipitation

Ajax gets around 78 mm of rain over 10.1 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 33% and peaks near 36% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
136
236
335
435
535
635
735
835
934
1034
1134
1234
1334
1434
1533
1633
1733
1832
1932
2031
2131
2231
2330
2430
2530
2630
2730
2830
2930
3030
3130

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 95% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)
110000
210000
310000
410000
510000
610000
710000
810000
910000
1010000
1110000
129910
139910
149910
159910
169820
179820
189730
199730
209640
219550
229361
239271
249181
259091
2689101
2788111
2887121
2987121
3085132
3184142

Wind in May

Winds average 16 km/h in May.

Across May, daily wind ranges from about 15 km/h on the calmest days to 17 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
117light breeze
217light breeze
317light breeze
417light breeze
516light breeze
616light breeze
716light breeze
816light breeze
916light breeze
1016light breeze
1116light breeze
1216light breeze
1316light breeze
1416light breeze
1516light breeze
1616light breeze
1716light breeze
1816light breeze
1916light breeze
2016light breeze
2116light breeze
2215light breeze
2315light breeze
2415light breeze
2515light breeze
2615light breeze
2715light breeze
2815light breeze
2915light breeze
3015light breeze
3115light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 54 min at the start of May to 15 hours by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 66 minutes over May. Sunrise moves from 5:16 AM to 4:44 AM, and sunset from 7:11 PM to 7:43 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.95:167:11
214.05:147:12
314.05:137:13
414.15:117:14
514.15:107:16
614.15:097:17
714.25:077:18
814.25:067:19
914.35:057:20
1014.35:037:22
1114.35:027:23
1214.45:017:24
1314.45:007:25
1414.54:597:26
1514.54:577:27
1614.54:567:28
1714.64:557:29
1814.64:547:31
1914.64:537:32
2014.74:527:33
2114.74:517:34
2214.74:507:35
2314.84:497:36
2414.84:497:37
2514.84:487:38
2614.94:477:39
2714.94:467:40
2814.94:467:41
2914.94:457:42
3015.04:447:43
3115.04:447:43

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.93 kWh/m².

For context, solar energy here swings from a low near 1.28 kWh/m² to a high of 6.32 kWh/m² in June across the year — May's 5.93 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.6Bright
45.6Bright
55.7Bright
65.7Bright
75.7Bright
85.7Bright
95.8Bright
105.8Bright
115.8Bright
125.8Bright
135.8Bright
145.9Bright
155.9Bright
165.9Bright
176.0Bright
186.0Bright
196.0Intense
206.0Intense
216.0Intense
226.1Intense
236.1Intense
246.1Intense
256.1Intense
266.1Intense
276.1Intense
286.1Intense
296.1Intense
306.1Intense
316.2Intense
Planning a trip in May

Is May a good time to visit Ajax?

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

3.0
Sightseeing
6th-best month of the year
0.0
Beach & pool
6th-best month of the year

May is a weaker month for outdoor sightseeing in Ajax.

What to pack for Ajax in May

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

In May, Ajax sees daytime highs around 12°C and nights near 8°C. Pack a warm layer. Worth having: rain gear and sun protection. About 10 days see rain.

a warm layerrain gearsun protection

Sea temperature near Ajax in May

The nearest coast averages about 7°C in May — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 13 km away) is warmest in August at about 21°C and coldest in March near 3°C.

It's comfortable for a long swim from Jul 27 to Sep 2 — about 1.2 months when the water holds above 20°C.

0°10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarm
Sea temperature (°C)Comfort
Jan4Bracing
Feb3Bracing
Mar3Bracing
Apr4Bracing
May7Bracing
Jun14Bracing
Jul19Cool
Aug21Refreshing
Sep19Cool
Oct13Bracing
Nov8Bracing
Dec5Bracing

UV index in Ajax 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 Ajax peaks around June 21 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 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 highHighModerateLowJun 21UV 8Dec 21UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar4Moderate
Apr5High
May6High
Jun8Very high
Jul8Very high
Aug6High
Sep5High
Oct3Moderate
Nov2Low
Dec1Low

Air quality in Ajax 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 Ajax is worst in May — around 21 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (November, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodMay 2021 µg/m³Nov 2310 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar17Moderate
Apr18Moderate
May21Moderate
Jun20Moderate
Jul20Moderate
Aug17Moderate
Sep16Moderate
Oct11Good
Nov10Good
Dec10Good
Location & terrain

Where is Ajax?

Ajax sits at 43.9°N, 79.0°W, 97 m above sea level, in Canada. The nearest listed city is Whitby, 9.0 km away.

Topography around Ajax

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

Within 3 km, the terrain around Ajax has only modest variations in elevation — a maximum elevation change of 62 m around an average of 95 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 215 m; within 80 km, significant variations in elevation — a maximum elevation change of 484 m.

The land around Ajax is covered by artificial surfaces (53%) and trees (28%) within 3 km, water (35%) and trees (23%) within 16 km, and water (39%) and trees (24%) within 80 km.

3 km
62 m
16 km
215 m
80 km
484 m
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
May weather nearby: Whitby 9.0 km · Pickering 10 km · Rouge 12 km · Brooklin 13 km · West Hill 15 km · Morningside 16 km · Oshawa 16 km · Malvern 16 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 Ajax (43.8501°, -79.0329°, elevation 97 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).