St. John's weather in September

In September, St. John's sees average daytime highs of 28°C and overnight lows near 26°C, with 127 mm of rain across 18 wet days and about 12.1 hours of daylight. It is the 1st-warmest and 2nd-wettest month of the year here.

Day-to-day highs hold fairly steady near 28°C through the month. The sky is clear or mostly clear about 36% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 18 min at the start of September to 11 h 54 min by month's end. Set against the rest of the year, September is St. John's's 12th-clearest and 11th-windiest month. For the whole year in context, see St. John's's year-round climate.

Daytime high
28°
1st warmest
Overnight low
26°
12th coldest
Rainfall
127 mm
18 wet days
Daylight
12 h 06 min
5:59 AM – 6:05 PM
Cloud cover
59%
12th clearest
Wind
22 km/h
11th windiest
Solar energy
5.96 kWh/m²
Travel score
4.9
out of 10

St. John's is largest city of Antigua and Barbuda.

Density
5,174/km²
people per km²
Founded
1666

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 28°C through the month.

A typical September day in St. John's reaches about 28°C in the afternoon and slips back to 26°C overnight — a 2°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 29°C. Set against its neighbours, September runs on par with August and on par with October.

24°26°28°30°32°151015202530
Avg high (°C)Avg low (°C)
12826
22826
32826
42826
52826
62826
72826
82826
92826
102826
112826
122826
132826
142826
152826
162826
172826
182826
192826
202826
212826
222826
232826
242826
252826
262826
272826
282826
292826
302826

How September really feels in St. John's

Once humidity and wind are folded in, September averages 16 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
16
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

St. John's weather by month

How September compares with the rest of the year at a glance. September is the 1st-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan26° / 24°321011.17.3
Feb25° / 24°217.111.47.7
Mar25° / 24°216.611.97.8
Apr26° / 25°338.812.47.2
May27° / 26°6212.412.86.3
Jun27° / 26°5112.1136.1
Jul28° / 26°7815.912.95.8
Aug28° / 26°9817.812.65.4
Sep28° / 26°1271812.14.9
Oct28° / 26°13218.811.65.2
Nov27° / 26°10315.811.25.8
Dec26° / 25°5813.3116.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 36% of the time in September, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 50%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15743
25743
35743
45545
55545
65545
75347
85347
95248
105149
115149
124951
134951
144852
154951
164852
174852
184753
194753
204753
214654
224654
234654
244654
254654
264753
274852
284852
294852
304852

Chance of precipitation in September

Any precipitation

St. John's gets around 127 mm of rain over 18 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 60% and peaks near 62% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
158
258
357
457
557
657
757
858
958
1058
1159
1259
1360
1460
1560
1660
1761
1861
1961
2062
2162
2262
2362
2462
2562
2662
2762
2862
2962
3062

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the oppressive band about 53% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
14654
24654
34654
44654
54654
64654
74753
84753
94852
104852
114951
125050
135149
145248
155347
165446
175545
185644
195644
205743
215842
225842
235941
245941
256040
266040
276139
286139
296238
306238

Wind in September

Winds average 22 km/h in September.

Across September, daily wind ranges from about 21 km/h on the calmest days to 23 km/h at its breeziest. It stays fairly steady from day to day.

0102030151015202530
Wind speed (km/h)Feels
123breezy
223breezy
323breezy
423breezy
523breezy
623breezy
723breezy
823breezy
923breezy
1023breezy
1123breezy
1223breezy
1323breezy
1422breezy
1522breezy
1622breezy
1722breezy
1822breezy
1922breezy
2022breezy
2122breezy
2222breezy
2322breezy
2422breezy
2521breezy
2621breezy
2721breezy
2821breezy
2921breezy
3021breezy

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 18 min at the start of September to 11 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 24 minutes over September. Sunrise moves from 5:57 AM to 6:01 AM, and sunset from 6:17 PM to 5:53 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.35:576:17
212.35:576:16
312.35:576:16
412.35:576:15
512.35:576:14
612.35:586:13
712.25:586:12
812.25:586:11
912.25:586:11
1012.25:586:10
1112.25:586:09
1212.25:586:08
1312.15:586:07
1412.15:596:06
1512.15:596:05
1612.15:596:05
1712.15:596:04
1812.15:596:03
1912.05:596:02
2012.05:596:01
2112.05:596:00
2212.06:005:59
2312.06:005:58
2412.06:005:58
2511.96:005:57
2611.96:005:56
2711.96:005:55
2811.96:005:54
2911.96:015:53
3011.96:015:53

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.96 kWh/m².

For context, solar energy here swings from a low near 4.61 kWh/m² to a high of 6.7 kWh/m² in April across the year — September's 5.96 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.2Intense
26.2Intense
36.2Intense
46.2Intense
56.2Intense
66.1Intense
76.1Intense
86.1Intense
96.1Intense
106.1Intense
116.1Intense
126.0Intense
136.0Intense
146.0Intense
156.0Bright
166.0Bright
175.9Bright
185.9Bright
195.9Bright
205.9Bright
215.8Bright
225.8Bright
235.8Bright
245.8Bright
255.8Bright
265.8Bright
275.7Bright
285.7Bright
295.7Bright
305.7Bright
Planning a trip in September

Hazard calendar for St. John's

In seasonPeak

In September, St. John's sits inside its atlantic hurricane and rainy season season. The full year is below, with each hazard's peak months called out.

St. John's sits in the Atlantic hurricane belt; the season peaks August–October.

St. John's's rainy season runs July–November, when most of the year's rain falls.

St. John's sees seasonal dust haze (July), heaviest in July.

Atlantic hurricane
Rainy season
Dust
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit St. John's?

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

4.9
Sightseeing
12th-best month of the year
5.6
Beach & pool
11th-best month of the year

September is a reasonable time to visit St. John's for sightseeing.

What to pack for St. John's in September

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

In September, St. John's sees daytime highs around 28°C and nights near 26°C. Pack light clothes and rain gear. Worth having: sun protection and a windbreaker. About 18 days see rain.

light clothesrain gearsun protectiona windbreaker

Sea temperature near St. John's in September

The nearest coast averages about 29°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in September at about 29°C and coldest in February near 26°C.

The water stays above 20°C all year — warm enough for a swim any month.

24°26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan27Warm
Feb26Warm
Mar26Warm
Apr27Warm
May27Warm
Jun28Warm
Jul28Tropical
Aug29Tropical
Sep29Tropical
Oct29Tropical
Nov28Tropical
Dec27Warm

UV index in St. John's in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 12 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in St. John's peaks around April 10 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 7 (very high).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeVery highApr 10UV 13Dec 16UV 7
UV index (midday)Level
Jan8Very high
Feb11Extreme
Mar13Extreme
Apr13Extreme
May12Extreme
Jun12Extreme
Jul12Extreme
Aug11Extreme
Sep12Extreme
Oct10Extreme
Nov8Very high
Dec7Very high

Air quality in St. John's in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in St. John's is worst in July — around 24 µg/m³ PM2.5 (moderate), about 3.2× the cleanest month (December, 8 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1124 µg/m³Dec 238 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb10Good
Mar9Good
Apr11Good
May14Moderate
Jun24Moderate
Jul24Moderate
Aug20Moderate
Sep16Moderate
Oct17Moderate
Nov11Good
Dec8Good
Location & terrain

Where is St. John's?

St. John's sits at 17.1°N, 61.8°W, 12 m above sea level, in Antigua and Barbuda. The nearest listed city is Falmouth, 12 km away.

FalmouthEnglish HarbourCodrington

Topography around St. John's

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

Within 3 km, the terrain around St. John's has only modest variations in elevation — a maximum elevation change of 109 m around an average of 20 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 391 m; within 80 km, large variations in elevation — a maximum elevation change of 1,011 m.

The land around St. John's is covered by artificial surfaces (35%) and trees (31%) within 3 km, water (69%) within 16 km, and water (96%) within 80 km.

3 km
109 m
16 km
391 m
80 km
1,011 m
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Falmouth 12 km · English Harbour 14 km · Brades 54 km · Codrington 58 km · Plymouth 61 km · Sainte-Rose 89 km · Basseterre 96 km · Baie-Mahault 99 km

Antigua and Barbuda travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B
230 V · 60 Hz
Prices
≈ 69% of US
price level, 2025
GDP per capita
$24,819
2025
Homicide rate
10.7
per 100k, 2023
Road deaths
0
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 68%other 12%Roman Catholic 8%none 6%

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. John's (17.121°, -61.8433°, elevation 12 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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).