Saint John weather in September

In September, Saint John sees average daytime highs of 16°C and overnight lows near 12°C, with 108 mm of rain across 10 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 18°C in the first days to 15°C by the end. The sky is clear or mostly clear about 31% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 06 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Saint John's 1st-clearest and 8th-windiest month. For the whole year in context, see Saint John's year-round climate.

Daytime high
16°
3rd warmest
Overnight low
12°
10th coldest
Rainfall
108 mm
10 wet days
Daylight
12 h 18 min
6:09 AM – 6:28 PM
Cloud cover
59%
1st clearest
Wind
16 km/h
8th windiest
Solar energy
3.92 kWh/m²
Travel score
5.1
out of 10

Saint John is city in New Brunswick, Canada.

Air quality
Excellent
PM2.5 5 µg/m³ · 2019
Density
227/km²
people per km²
Founded
1604

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 18°C in the first days to 15°C by the end.

A typical September day in Saint John reaches about 16°C in the afternoon and slips back to 12°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 14°C and 19°C. Set against its neighbours, September runs about 2°C cooler than August and about 4°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
11814
21814
31813
41813
51713
61713
71713
81713
91713
101713
111713
121712
131712
141612
151612
161612
171612
181612
191612
201611
211611
221611
231511
241511
251511
261511
271510
281510
291510
301410

How September really feels in Saint John

Once humidity and wind are folded in, September 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

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

Saint John weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-2° / -9°11211.68.48.90.0
Feb-1° / -8°9510.38.210.10.0
Mar / -4°11211.47.211.60.0
Apr / 10512.33.413.20.5
May11° / 10412.30.214.62.4
Jun15° / 11°10812.1015.44.3
Jul18° / 14°9111015.15.6
Aug19° / 14°819.3013.96.1
Sep16° / 12°10810012.35.1
Oct12° / 13310.90.210.73.1
Nov / 12811.82.39.30.8
Dec / -4°13713.16.98.60.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 31% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 53%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14852
24753
34753
44654
54654
64654
74654
84753
94654
104654
114654
124654
134555
144555
154654
164753
174753
184654
194654
204654
214654
224753
234753
244753
254753
264654
274753
284753
294753
304753

Chance of precipitation in September

Any precipitation

Saint John gets around 108 mm of rain over 10 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 32% and peaks near 35% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
129
230
331
431
532
632
733
833
933
1032
1132
1232
1332
1432
1532
1632
1732
1832
1932
2032
2132
2233
2333
2433
2534
2634
2734
2835
2935
3035

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 65% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
14541131
24740121
34839121
45038111
55138110
65337100
75436100
8563590
9573580
10583480
11593470
12603370
13623260
14633160
15653050
16662950
17682840
18692740
19702640
20712540
21722440
22732340
23752140
24762040
25771940
26801730
27811630
28821530
29831430
30851230

Wind in September

Winds average 16 km/h in September.

Across September, daily wind ranges from about 15 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
115light breeze
215light breeze
315light breeze
415light breeze
515light breeze
615light 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
2217light breeze
2317light breeze
2417light breeze
2517light breeze
2617light breeze
2717light breeze
2817light breeze
2917light breeze
3018light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 06 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 90 minutes over September. Sunrise moves from 5:50 AM to 6:27 AM, and sunset from 6:57 PM to 6:00 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.15:506:57
213.15:526:55
313.05:536:54
413.05:546:52
512.95:556:50
612.95:576:48
712.85:586:46
812.75:596:44
912.76:006:42
1012.66:026:40
1112.66:036:38
1212.56:046:36
1312.56:056:34
1412.46:076:32
1512.46:086:30
1612.36:096:28
1712.36:106:26
1812.26:126:24
1912.16:136:22
2012.16:146:20
2112.06:156:18
2212.06:176:16
2311.96:186:14
2411.96:196:12
2511.86:216:10
2611.86:226:08
2711.76:236:06
2811.76:246:04
2911.66:266:02
3011.66:276:00

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.92 kWh/m².

For context, solar energy here swings from a low near 1.28 kWh/m² to a high of 5.62 kWh/m² in June across the year — September's 3.92 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.6Bright
24.5Bright
34.5Bright
44.4Bright
54.4Bright
64.3Bright
74.3Bright
84.2Bright
94.2Bright
104.2Bright
114.1Bright
124.1Bright
134.0Bright
144.0Moderate
153.9Moderate
163.9Moderate
173.9Moderate
183.8Moderate
193.8Moderate
203.7Moderate
213.7Moderate
223.6Moderate
233.6Moderate
243.5Moderate
253.5Moderate
263.5Moderate
273.4Moderate
283.4Moderate
293.3Moderate
303.3Moderate
Planning a trip in September

Is September a good time to visit Saint John?

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

5.1
Sightseeing
3rd-best month of the year
0.9
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Saint John for sightseeing.

What to pack for Saint John in September

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

In September, Saint John sees daytime highs around 16°C and nights near 12°C. Worth packing: a warm layer and rain gear. About 10 days see rain.

a warm layerrain gear

Sea temperature near Saint John in September

The nearest coast averages about 13°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 17 km away) is warmest in August at about 14°C and coldest in March near 2°C.

The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.

0°5°10°15°JanFebMarAprMayJunJulAugSepOctNovDecbracingcool
Sea temperature (°C)Comfort
Jan5Bracing
Feb3Bracing
Mar2Bracing
Apr3Bracing
May6Bracing
Jun9Bracing
Jul13Bracing
Aug14Bracing
Sep13Bracing
Oct12Bracing
Nov10Bracing
Dec7Bracing

UV index in Saint John in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Saint John peaks around July 11 at about 7 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near January 1 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 highHighModerateLowJul 11UV 7Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar3Moderate
Apr5Moderate
May7High
Jun7Very high
Jul7Very high
Aug6High
Sep5Moderate
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Saint John?

Saint John sits at 45.3°N, 66.1°W, 30 m above sea level, in Canada. The nearest listed city is Saint John West, 2.0 km away.

Topography around Saint John

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

Within 3 km, the terrain around Saint John has only modest variations in elevation — a maximum elevation change of 95 m around an average of 16 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 234 m; within 80 km, significant variations in elevation — a maximum elevation change of 449 m.

The land around Saint John is covered by water (38%), artificial surfaces (29%) and trees (21%) within 3 km, trees (52%) and water (38%) within 16 km, and trees (49%) and water (45%) within 80 km.

3 km
95 m
16 km
234 m
80 km
449 m
treesgrasslandartificial surfacesbare terrainwaterwetland
September weather nearby: Saint John West 2.0 km · Quispamsis 19 km · Fredericton 89 km · Fredericton Northside 91 km · Riverview 130 km · Lutes Mountain 131 km · Moncton 134 km · Dieppe 139 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 Saint John (45.2708°, -66.0562°, elevation 30 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).