St. Catharines in Summer
In summer (June, July and August), St. Catharines sees average daytime highs around 23°C and overnight lows near 18°C, with 254 mm of rain over about 32 wet days across the season. It is the warmest season of the year and the 2nd-wettest season.
Over the season highs climb from about 19°C in early June to 23°C by late August. The sky is clear or mostly clear about 36% of the time across summer, and the air most often feels humid.
Summer is St. Catharines's best season of the year to visit on our travel score. For the whole year in context, see St. Catharines's year-round climate.
- Avg daytime high
- 23°C
- warmest season of the year
- Avg overnight low
- 18°C
- Rainfall
- 254 mm
- 32 wet days
- Avg wind
- 12 km/h
- Travel score
- 6.8
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in St. Catharines in Summer
Over the season highs climb from about 19°C in early June to 23°C by late August.
A typical summer day in St. Catharines reaches about 23°C and drops to 18°C overnight. The warmest of the three months is July, the coolest June.
How summer really feels in St. Catharines
Once humidity and wind are folded in, summer brings about 0 days that feel above 32°C and 0 that feel at or below 0°C.
summer sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.
St. Catharines weather by month
How the three summer months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | -0° / -5° | 75 | 11.9 | 9 | 9.2 | 0.0 |
| Feb | -0° / -6° | 59 | 9 | 7 | 10.2 | 0.0 |
| Mar | 4° / -2° | 73 | 10.4 | 4.6 | 11.6 | 0.1 |
| Apr | 9° / 4° | 97 | 11.7 | 1.8 | 13.1 | 1.8 |
| May | 15° / 10° | 83 | 11.4 | 0 | 14.4 | 4.5 |
| Jun | 21° / 16° | 91 | 11.1 | 0 | 15.1 | 6.4 |
| Jul | 25° / 20° | 88 | 10.8 | 0 | 14.9 | 6.9 |
| Aug | 24° / 19° | 75 | 9.9 | 0 | 13.8 | 7.1 |
| Sep | 21° / 16° | 85 | 9.8 | 0 | 12.3 | 6.5 |
| Oct | 14° / 9° | 92 | 12.1 | 0.1 | 10.8 | 4.1 |
| Nov | 8° / 4° | 82 | 10.8 | 2 | 9.5 | 1.3 |
| Dec | 3° / -1° | 77 | 11.6 | 6.6 | 8.9 | 0.0 |
Cloud cover in Summer
The sky is clear or mostly clear about 36% of the time across summer.
Chance of precipitation in Summer
St. Catharines gets around 254 mm of rain over 32 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels humid — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 12 km/h across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 54 min in early June to 13 h 06 min by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 5.9 kWh/m².
Is summer a good time to visit St. Catharines?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a reasonable time to visit St. Catharines for sightseeing.
What to pack for St. Catharines in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, St. Catharines sees daytime highs around 23°C and nights near 18°C. Pack sun protection. Worth having: light clothes and rain gear. About 32 days see rain.
Sea temperature near St. Catharines in Summer
The nearest coast averages about 19°C across summer — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 25 km away) is warmest in August at about 22°C and coldest in February near 3°C.
It's comfortable for a long swim from Jul 17 to Sep 6 — about 1.7 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 4 | 3 | 3 | 4 | 7 | 15 | 20 | 22 | 19 | 13 | 8 | 5 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Refreshing | Refreshing | Cool | Bracing | Bracing | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 4 | Bracing |
| Feb | 3 | Bracing |
| Mar | 3 | Bracing |
| Apr | 4 | Bracing |
| May | 7 | Bracing |
| Jun | 15 | Bracing |
| Jul | 20 | Refreshing |
| Aug | 22 | Refreshing |
| Sep | 19 | Cool |
| Oct | 13 | Bracing |
| Nov | 8 | Bracing |
| Dec | 5 | Bracing |
UV index in St. Catharines in Summer
Clear-sky midday UV across summer averages 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 St. Catharines peaks around June 19 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. 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 8 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 2 | 4 | 5 | 6 | 8 | 7 | 6 | 5 | 3 | 2 | 1 |
| Level | Low | Moderate | Moderate | High | High | Very high | Very high | High | High | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 2 | Moderate |
| Mar | 4 | Moderate |
| Apr | 5 | High |
| May | 6 | High |
| Jun | 8 | Very high |
| Jul | 7 | Very high |
| Aug | 6 | High |
| Sep | 5 | High |
| Oct | 3 | Moderate |
| Nov | 2 | Low |
| Dec | 1 | Low |
Where is St. Catharines?
St. Catharines sits at 43.2°N, 79.2°W, 102 m above sea level, in Canada. The nearest listed city is Thorold, 7.0 km away.
Topography around St. Catharines
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of St. Catharines.
Within 3 km, the terrain around St. Catharines has only modest variations in elevation — a maximum elevation change of 47 m around an average of 100 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 193 m; within 80 km, significant variations in elevation — a maximum elevation change of 483 m.
The land around St. Catharines is covered by artificial surfaces (51%) and trees (33%) within 3 km, water (33%) and trees (20%) within 16 km, and water (41%) and trees (24%) within 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
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 St. Catharines (43.1713°, -79.2427°, elevation 102 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.