Castries weather in December

In December, Castries sees average daytime highs of 28°C and overnight lows near 25°C, with 42 mm of rain across 13 wet days and about 11.2 hours of daylight. It is the 9th-warmest and 8th-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 56% of the time in December, and the air most often feels oppressive.

Daylight stretches from about 11 h 12 min at the start of December to 11 h 12 min by month's end. Set against the rest of the year, December is Castries's 3rd-clearest and 6th-windiest month. For the whole year in context, see Castries's year-round climate.

Daytime high
28°
9th warmest
Overnight low
25°
5th coldest
Rainfall
42 mm
13 wet days
Daylight
11 h 12 min
6:25 AM – 5:36 PM
Cloud cover
44%
3rd clearest
Wind
21 km/h
6th windiest
Solar energy
4.95 kWh/m²
Travel score
5.7
out of 10

Castries is capital of Saint Lucia.

Density
253/km²
people per km²
Founded
1650

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

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

A typical December day in Castries reaches about 28°C in the afternoon and slips back to 25°C overnight — a 4°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, December runs on par with November and on par with January.

20°23°25°28°30°151015202531
Avg high (°C)Avg low (°C)
12825
22825
32825
42825
52825
62825
72825
82825
92825
102825
112825
122825
132825
142825
152825
162825
172825
182824
192824
202824
212824
222824
232824
242824
252824
262824
272824
282824
292824
302824
312824

How December really feels in Castries

Once humidity and wind are folded in, December 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

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

Castries weather by month

How December compares with the rest of the year at a glance. December is the 9th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan28° / 24°3111.811.36.5
Feb28° / 24°218.811.56.7
Mar28° / 24°269.811.96.1
Apr29° / 25°3611.512.35.4
May29° / 25°4712.512.64.9
Jun29° / 25°6515.112.84.5
Jul29° / 25°8320.312.74.2
Aug30° / 26°9920.712.54.0
Sep30° / 26°10419.412.13.9
Oct29° / 25°11920.911.74.0
Nov29° / 25°10218.911.44.5
Dec28° / 25°421311.25.7

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 56% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 20% of December, with mostly cloudy or overcast conditions the remaining 24%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16931
26931
37030
47030
57129
67129
77228
87228
97327
107327
117525
127525
137624
147624
157723
167723
177723
187723
197822
207822
217822
227822
237921
248020
258020
268119
278218
288218
298218
308416
318416

Chance of precipitation in December

Any precipitation

Castries gets around 42 mm of rain over 13 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 42% and peaks near 51% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202531
Rain chance (%)
151
249
348
447
546
646
745
844
944
1043
1142
1242
1341
1441
1540
1640
1740
1840
1940
2040
2140
2240
2340
2440
2540
2640
2741
2841
2941
3041
3142

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the oppressive band about 63% of days. Sticky, muggy-or-worse air turns up on roughly 98% of them.

0%25%50%75%100%151015202531
Humid (%)Muggy (%)Oppressive (%)
101882
212079
312178
412277
512475
612574
712673
812772
912871
1012970
1123068
1223167
1323266
1423365
1523464
1623563
1723662
1833760
1933859
2033958
2134057
2234156
2334255
2434354
2534453
2624553
2724751
2824850
2924949
3025147
3125246

Wind in December

Winds average 21 km/h in December.

Across December, daily wind ranges from about 19 km/h on the calmest days to 22 km/h at its breeziest. It stays fairly steady from day to day.

0510152025151015202531
Wind speed (km/h)Feels
119light breeze
219light breeze
320light breeze
420light breeze
520light breeze
620light breeze
720light breeze
820breezy
920breezy
1020breezy
1120breezy
1220breezy
1320breezy
1420breezy
1521breezy
1621breezy
1721breezy
1821breezy
1921breezy
2021breezy
2121breezy
2221breezy
2321breezy
2421breezy
2522breezy
2622breezy
2722breezy
2822breezy
2922breezy
3022breezy
3122breezy

Sunrise & sunset in December

DaylightNight

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

Days grow by about 0 minutes over December. Sunrise moves from 6:17 AM to 6:32 AM, and sunset from 5:31 PM to 5:43 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
111.26:175:31
211.26:175:31
311.26:185:31
411.26:185:31
511.26:195:32
611.26:205:32
711.26:205:32
811.26:215:33
911.26:215:33
1011.26:225:33
1111.26:225:34
1211.26:235:34
1311.26:235:34
1411.26:245:35
1511.26:245:35
1611.26:255:36
1711.26:255:36
1811.26:265:36
1911.26:265:37
2011.26:275:37
2111.26:275:38
2211.26:285:38
2311.26:285:39
2411.26:295:39
2511.26:295:40
2611.26:305:40
2711.26:305:41
2811.26:305:41
2911.26:315:42
3011.26:315:42
3111.26:325:43

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 4.95 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 4.95 kWh/m² to a high of 6.65 kWh/m² in April across the year — December's 4.95 kWh/m² sits near the bottom.

024151015202531
Solar energy (kWh/m²)Level
14.9Bright
24.9Bright
34.9Bright
44.9Bright
54.9Bright
64.9Bright
74.9Bright
84.9Bright
94.9Bright
104.9Bright
114.9Bright
124.9Bright
135.0Bright
145.0Bright
155.0Bright
165.0Bright
175.0Bright
185.0Bright
195.0Bright
205.0Bright
215.0Bright
225.0Bright
235.0Bright
245.0Bright
255.0Bright
265.0Bright
275.0Bright
285.0Bright
295.0Bright
305.0Bright
315.0Bright
Planning a trip in December

Hazard calendar for Castries

In seasonPeak

None of Castries's seasonal hazards are active in December. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

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

Castries's rainy season runs June–November, when most of the year's rain falls.

Castries sees seasonal dust haze (June–July), heaviest in June.

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

Is December a good time to visit Castries?

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

5.7
Sightseeing
4th-best month of the year
6.7
Beach & pool
5th-best month of the year

December is a reasonable time to visit Castries for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Castries in December

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

In December, Castries sees daytime highs around 28°C and nights near 25°C. Pack light clothes. Worth having: rain gear, sun protection and a windbreaker. About 13 days see rain.

light clothesrain gearsun protectiona windbreaker

Sea temperature near Castries in December

The nearest coast averages about 28°C in December — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 19 km away) is warmest in September at about 29°C and coldest in February near 27°C.

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

26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan27Warm
Feb27Warm
Mar27Warm
Apr27Warm
May28Warm
Jun28Warm
Jul28Tropical
Aug29Tropical
Sep29Tropical
Oct29Tropical
Nov29Tropical
Dec28Warm

UV index in Castries in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 8 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Castries peaks around March 21 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 13 at about 8 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highMar 21UV 14Dec 13UV 8
UV index (midday)Level
Jan9Very high
Feb12Extreme
Mar14Extreme
Apr13Extreme
May12Extreme
Jun11Extreme
Jul12Extreme
Aug11Extreme
Sep12Extreme
Oct11Extreme
Nov9Very high
Dec8Very high

Air quality in Castries in December

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Castries is worst in June — around 29 µg/m³ PM2.5 (moderate), about 2.9× the cleanest month (December, 10 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJun 1929 µg/m³Dec 2310 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb14Moderate
Mar12Good
Apr16Moderate
May19Moderate
Jun29Moderate
Jul25Moderate
Aug21Moderate
Sep15Moderate
Oct18Moderate
Nov13Moderate
Dec10Good
Location & terrain

Where is Castries?

Castries sits at 14.0°N, 61.0°W, 119 m above sea level, in Saint Lucia. The nearest listed city is Gros Islet, 10 km away.

Gros IsletSoufriereVieux Fort

Topography around Castries

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

Within 3 km, the terrain around Castries has significant variations in elevation — a maximum elevation change of 266 m around an average of 45 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 900 m; within 80 km, large variations in elevation — a maximum elevation change of 1,191 m.

The land around Castries is covered by trees (46%) and water (35%) within 3 km, water (55%) and trees (42%) within 16 km, and water (89%) within 80 km.

3 km
266 m
16 km
900 m
80 km
1,191 m
treesgrasslandartificial surfaceswaterwetland
December weather nearby: Gros Islet 10 km · Soufriere 16 km · Vieux Fort 32 km · Ducos 65 km · Fort-de-France 68 km · Le Lamentin 69 km · Le François 70 km · Saint-Joseph 75 km

Saint Lucia travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type A / B / G
240 V · 50 Hz
Prices
≈ 51% of US
price level, 2025
GDP per capita
$14,746
2025
Homicide rate
39
per 100k, 2023
Road deaths
29.8
per 100k/yr, 2019
Income group
Upper middle
World Bank
Religion
Roman Catholic 62%Protestant 26%none 6%other Christian 3%

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 Castries (13.9957°, -61.0061°, elevation 119 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).