St. John's, Newfoundland (St. John's) weather in September

September in St. John's, Newfoundland: nice, rainy, with clean air — a great time to visit.

Updated September 2026 · climate normals from ERA5 reanalysis

St. John's, Newfoundland🇨🇦 Canada · Northeast & Atlantic Canada · City77
  1. 33Jan
  2. 38Feb
  3. 46Mar
  4. 59Apr
  5. 71May
  6. 80Jun
  7. 90Jul
  8. 88Aug
  9. 77Sep
  10. 66Oct
  11. 51Nov
  12. 36Dec

#4 of 12 months in St. John's, Newfoundland · #809 of 1413 destinations to visit in September · comfort 77/100 (tier B)

Days
18°C
Nights
9°C
Wet days
10
Sun
7.3 h
Humidity
81%
Daylight
13 h
St. John's, Newfoundland, Canada
Photo: Daniel Battersby · Pexels

Traveller notes on St. John's, Newfoundland in September

September is one of the better months for weather here and the worst trade you can make for wildlife. The fog thins - this city averages 124 fog days a year, but they are far fewer after mid-July - and the coast clears. The icebergs, though, run March to about July, so late September offers little or no chance of one, and the puffins and whales are thinning too, with the humpbacks starting their move to calving grounds. Our row gives 18.3C days over 8.7C nights that feel like 6C, a 25.3 kph wind and a 12.9C sea. The record: 90.9mm across 10.2 days, 7.3 hours of sun and AQI 36.
GoodWeatherWrongMonthForBergs · September · 1 month ago · Read more on Tripadvisor ↗

Other months in St. John's, Newfoundland

Regulars are direct that this is the rainiest month of the year here, occasionally worsened by the remnants of a hurricane or tropical storm pushing in extra rain, and specifically recommend the first ten days as the sweet spot before it turns cooler and the odds of snow climb. Our row backs that cool, genuinely wet read, 13.1C over 4.1C nights feeling 0C, with 84.2mm of rain across 9.8 days and a trace of early snow, 0.1cm. Regulars are consistent the city itself stays fully in swing for visitors even as some seasonal attractions wind down, Signal Hill's visitor center specifically closing around the 10th of the month. The sea sits at a cold 9.4C. The record: humidity 80 percent, 5.6 hours of sun, a 26.1 kph wind and AQI 34.
RainiestMonthHereFirstTenDaysAreBest · October · 1 month ago · Read more on Tripadvisor ↗
May here is rain, wind and fog, and regulars say the variation is the real story: one day near freezing, the next 15C. Our row averages 11.7C but reads as 8C, with nights at 1.4C feeling like -3C in a 25 kph wind, 73.7mm across 11.6 days, and 2.1cm still sitting in the snow column. A hooded coat, because the rain and sleet here travel sideways, and a sweater underneath it. Icebergs are why many people come and nobody on the board will promise them: they drift on currents and pack ice, they turn up any time from March into July, and mid to late May is a good bet rather than a safe one. Dress for the boat - the sea is 1.5C. The record: humidity 80 percent, 8.6 hours of sun and AQI 35.
IcebergsNeverGuaranteed · May · 1 month ago · Read more on Tripadvisor ↗
June in St John's has a local name for its fog - capelin weather - blanket fog that can sit for days, and regulars are honest that it is the month's one real drawback in a month that is not warm to begin with. Our row gives 17.9C by day feeling like 16C, 7.1C at night, and a 4.5C sea. After mid-July it is less common. The trade they offer in exchange is the reason to come at all: the same capelin run brings the whales, and June is prime iceberg season, though the bergs that reach St John's, Bay Bulls and Ferryland have melted small by the time they get this far south. Mid-June averages nearer 18C by day and 12 at night. The record: 11.2 precipitation days carrying 81.4mm, humidity 84 percent and a 23.8 kph wind.
CapelinWeather · June · 1 month ago · Read more on Tripadvisor ↗
Late July is the best chance of good weather here, and the St John's forum still refuses to promise any: the standing line is that if you do not like it, wait, and posters say it is not unusual to get sun, rain, hail, sleet and snow in one day. Fog is the local specialty - the city averages 124 fog days a year, June's blanket capelin fogs being the worst of it, and they thin out after mid-July. That timing cuts the other way for icebergs: the season is May to June, so arriving mid-July makes sightings slim. Packing advice is shorts and short sleeves plus, always with you, long trousers, a fleece, a rain shell, a warm hat and gloves. The record: 22.8C days, 11.9C nights, 10 precipitation days, 84 percent humidity, an 11.4C sea.
CapelinWeatherLayers · July · 1 month ago · Read more on tripadvisor.ca ↗

Add your own note from St. John's, Newfoundland's card on the map.

St. John's, Newfoundland climate normals — September

Daytime high18°C / 65°F😎 nice
Nighttime low9°C / 48°F
Feels like (high)17°C / 63°F
Sea temperature13°C / 55°F🥶 cold sea
Rainfall91 mm / 3.6 in🌧 rainy
Rainy days10 days
Humidity81%💦 very humid
Dew point11°C / 51°F
Sunshine7.3 h/day
Daylight12.5 h
Wind25 km/h / 16 mph
Air quality (US AQI)36🍃 good

Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.

Crowds in St. John's, Newfoundland in September

How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.

BusySummer break in Canada(estimated)

JFMAMJJASOND

Peak crowdsBusyShoulder seasonQuiet

Best months for St. John's, Newfoundland's weather

Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).

Fair weatherSt. John's, Newfoundland's weather peaks June–August, best around July.

JFMAMJJASOND

Best weatherFair weatherToughest weather

What's on in St. John's, Newfoundland in September

Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.

  • Hazard

    Post-tropical storm season

    1 Sep – 31 Oct · usuallyHurricane season

    In some years the remains of an Atlantic hurricane cross the Avalon Peninsula: Igor in 2010 washed out roads across eastern Newfoundland and Larry came ashore near the city in 2021. Flights and ferries stop while one passes. Source ↗

What's on around the world in September →

Where is St. John's, Newfoundland?

Loading map…

St. John's, Newfoundland in September — FAQ

Is September a good time to visit St. John's, Newfoundland?
September in St. John's, Newfoundland: nice, rainy, with clean air — a great time to visit. It ranks #4 of 12 months for St. John's, Newfoundland on SeasonMap's comfort score (77/100).
What is the weather like in St. John's, Newfoundland in September?
In September, St. John's, Newfoundland averages a daily high of 18.3°C and a low of 8.7°C, with about 90.9 mm of rain over roughly 10.2 rainy days.
What is the air quality in St. John's, Newfoundland in September?
St. John's, Newfoundland has a mean US Air Quality Index of about 36 in September.