Saint Croix weather in September

In September, Saint Croix sees average daytime highs of 28°C and overnight lows near 27°C, with 137 mm of rain across 17.6 wet days and about 12.1 hours of daylight. It is the 1st-warmest and 1st-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 miserable.

Daylight stretches from about 12 h 24 min at the start of September to 11 h 54 min by month's end. Set against the rest of the year, September is Saint Croix's 12th-clearest and 11th-windiest month. For the whole year in context, see Saint Croix's year-round climate.

Daytime high
28°
1st warmest
Overnight low
27°
12th coldest
Rainfall
137 mm
17.6 wet days
Daylight
12 h 06 min
6:10 AM – 6:16 PM
Cloud cover
58%
12th clearest
Wind
22 km/h
11th windiest
Solar energy
5.86 kWh/m²
Travel score
4.8
out of 10

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 Saint Croix reaches about 28°C in the afternoon and slips back to 27°C overnight — a 2°C spread between the day's warmth and the night's chill. On most days the high lands between 28°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)
12827
22827
32827
42827
52827
62827
72827
82827
92827
102827
112827
122827
132827
142827
152827
162827
172827
182827
192827
202827
212827
222827
232827
242827
252827
262827
272827
282827
292827
302827

How September really feels in Saint Croix

Once humidity and wind are folded in, September averages 30 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
30
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.

Saint Croix weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan26° / 25°278.311.17.6
Feb26° / 24°185.911.47.9
Mar26° / 24°206.111.97.9
Apr26° / 25°327.512.47.4
May27° / 26°7512.312.86.3
Jun28° / 26°5811.7136.1
Jul28° / 26°8014.6135.9
Aug28° / 27°10416.912.65.1
Sep28° / 27°13717.612.14.8
Oct28° / 26°12717.911.65.2
Nov27° / 26°11615.511.25.9
Dec26° / 25°4811.7116.9

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 15% of September, with mostly cloudy or overcast conditions the remaining 48%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15248
25347
35347
45347
55347
65347
75347
85347
95347
105347
115347
125347
135347
145347
155248
165248
175248
185149
195149
205050
215050
225050
235050
244951
254951
265050
275050
285050
295050
305050

Chance of precipitation in September

Any precipitation

Saint Croix gets around 137 mm of rain over 17.6 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 59% and peaks near 62% on the wettest days.

0%20%40%60%151015202530
Rain chance (%)
156
256
356
455
555
655
755
855
956
1056
1157
1257
1358
1459
1559
1660
1760
1861
1961
2061
2162
2262
2362
2462
2562
2662
2762
2861
2961
3061

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the miserable band about 61% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
13367
23367
33466
43466
53466
63466
73466
83466
93466
103565
113565
123565
133565
143664
153664
163664
173763
183862
193961
204060
214159
224357
234456
244555
254654
264852
274951
285050
295248
305347

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.

0510152025151015202530
Wind speed (km/h)Feels
123breezy
223breezy
323breezy
423breezy
523breezy
622breezy
722breezy
822breezy
922breezy
1022breezy
1122breezy
1222breezy
1322breezy
1422breezy
1522breezy
1622breezy
1722breezy
1822breezy
1922breezy
2021breezy
2121breezy
2221breezy
2321breezy
2421breezy
2521breezy
2621breezy
2721breezy
2821breezy
2921breezy
3021breezy

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 24 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 30 minutes over September. Sunrise moves from 6:08 AM to 6:13 AM, and sunset from 6:29 PM to 6:04 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.46:086:29
212.36:086:28
312.36:086:28
412.36:096:27
512.36:096:26
612.36:096:25
712.36:096:24
812.26:096:23
912.26:096:22
1012.26:096:22
1112.26:106:21
1212.26:106:20
1312.26:106:19
1412.16:106:18
1512.16:106:17
1612.16:106:16
1712.16:106:15
1812.16:116:15
1912.06:116:14
2012.06:116:13
2112.06:116:12
2212.06:116:11
2312.06:116:10
2412.06:126:09
2511.96:126:08
2611.96:126:07
2711.96:126:07
2811.96:126:06
2911.96:126:05
3011.96:136:04

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.86 kWh/m².

For context, solar energy here swings from a low near 4.52 kWh/m² to a high of 6.65 kWh/m² in April across the year — September's 5.86 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.2Intense
26.1Intense
36.1Intense
46.1Intense
56.1Intense
66.1Intense
76.1Intense
86.0Intense
96.0Intense
106.0Bright
116.0Bright
125.9Bright
135.9Bright
145.9Bright
155.9Bright
165.8Bright
175.8Bright
185.8Bright
195.8Bright
205.8Bright
215.7Bright
225.7Bright
235.7Bright
245.7Bright
255.7Bright
265.6Bright
275.6Bright
285.6Bright
295.6Bright
305.6Bright
Planning a trip in September

Hazard calendar for Saint Croix

In seasonPeak

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

Saint Croix sits in the Atlantic hurricane belt; the season peaks August–October.

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

Saint Croix 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 Saint Croix?

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

4.8
Sightseeing
12th-best month of the year
5.7
Beach & pool
12th-best month of the year

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

What to pack for Saint Croix in September

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

In September, Saint Croix sees daytime highs around 28°C and nights near 27°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 Saint Croix 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 at the nearest coast (about 17 km away) 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
May28Warm
Jun28Tropical
Jul28Tropical
Aug29Tropical
Sep29Tropical
Oct29Tropical
Nov28Tropical
Dec28Warm

UV index in Saint Croix 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 Saint Croix peaks around April 12 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 12UV 13Dec 16UV 7
UV index (midday)Level
Jan8Very high
Feb10Extreme
Mar13Extreme
Apr13Extreme
May11Extreme
Jun12Extreme
Jul11Extreme
Aug11Extreme
Sep12Extreme
Oct10Very high
Nov8Very high
Dec7High

Air quality in Saint Croix 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 Saint Croix is worst in July — around 24 µg/m³ PM2.5 (moderate), about 4.2× the cleanest month (December, 6 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1124 µg/m³Dec 236 µg/m³
PM2.5 (µg/m³)Level
Jan6Good
Feb8Good
Mar7Good
Apr9Good
May14Moderate
Jun23Moderate
Jul24Moderate
Aug20Moderate
Sep15Moderate
Oct15Moderate
Nov9Good
Dec6Good
Location & terrain

Where is Saint Croix?

Saint Croix sits at 17.7°N, 64.7°W, 87 m above sea level, in U.S. Virgin Islands. The nearest listed city is Charlotte Amalie, 71 km away.

Charlotte AmalieRoad Town

Topography around Saint Croix

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

Within 3 km, the terrain around Saint Croix has only modest variations in elevation — a maximum elevation change of 177 m around an average of 57 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 346 m; within 80 km, significant variations in elevation — a maximum elevation change of 512 m.

The land around Saint Croix is covered by trees (52%) and artificial surfaces (31%) within 3 km, water (74%) within 16 km, and water (96%) within 80 km.

3 km
177 m
16 km
346 m
80 km
512 m
treesshrubsgrasslandartificial surfacesbare terrainwater
September weather nearby: Charlotte Amalie 71 km · Road Town 79 km · Fajardo 117 km · Humacao 124 km · Carolina 147 km · Guayama 147 km · Caguas 149 km · Trujillo Alto 150 km

U.S. Virgin Islands travel facts

Power plugs
Type A / B
110 V · 60 Hz
Prices
≈ 89% of US
price level, 2022
GDP per capita
$44,321
2022
Safe drinking water
99%
of population, 2024
Homicide rate
49.9
per 100k, 2012
Income group
High
World Bank

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 Croix (17.7275°, -64.747°, elevation 87 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).