São Sebastião do Caí weather in December

In December, São Sebastião do Caí sees average daytime highs of 28°C and overnight lows near 18°C, with 182 mm of rain across 15.1 wet days and about 13.9 hours of daylight. It is the 3rd-warmest and 3rd-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 32% of the time in December, and the air most often feels muggy.

Daylight stretches from about 13 h 48 min at the start of December to 13 h 54 min by month's end. Set against the rest of the year, December is São Sebastião do Caí's 6th-clearest and 6th-windiest month. For the whole year in context, see São Sebastião do Caí's year-round climate.

Daytime high
28°
3rd warmest
Overnight low
18°
10th coldest
Rainfall
182 mm
15.1 wet days
Daylight
13 h 54 min
6:25 AM – 8:18 PM
Cloud cover
59%
6th clearest
Wind
9 km/h
6th windiest
Solar energy
6.44 kWh/m²
Travel score
5.4
out of 10

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 São Sebastião do Caí reaches about 28°C in the afternoon and slips back to 18°C overnight — a 10°C spread between the day's warmth and the night's chill. On most days the high lands between 23°C and 32°C. Set against its neighbours, December runs about 2°C warmer than November and on par with January.

10°15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
12717
22717
32717
42717
52717
62717
72817
82817
92817
102817
112817
122817
132817
142818
152818
162818
172818
182818
192818
202818
212818
222918
232918
242918
252918
262918
272919
282919
292919
302919
312919

São Sebastião do Caí weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan29° / 19°20917.613.74.7
Feb28° / 19°18016.613.14.8
Mar27° / 18°15415.212.25.8
Apr24° / 15°14211.211.36.6
May21° / 12°13610.410.56.4
Jun19° / 10°14410.310.16.0
Jul19° / 18010.810.36.0
Aug21° / 11°14510.710.96.4
Sep22° / 12°17812.511.86.1
Oct24° / 14°21614.812.76.0
Nov26° / 16°16412.813.56.2
Dec28° / 18°18215.113.95.4

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 32% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 18% of December, with mostly cloudy or overcast conditions the remaining 50%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14951
24951
34951
45050
55050
64951
75050
84951
95050
105050
115050
125149
135149
145149
155248
165248
175149
185149
195149
205149
215149
225149
235050
245050
255050
265050
274951
284951
294951
304951
314951

Chance of precipitation in December

Any precipitation

São Sebastião do Caí gets around 182 mm of rain over 15.1 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 48% and peaks near 50% on the wettest days.

0%20%40%60%151015202531
Rain chance (%)
147
247
347
447
547
647
748
848
948
1048
1148
1248
1348
1448
1548
1648
1748
1848
1948
2048
2149
2249
2349
2449
2549
2649
2749
2850
2950
3050
3150

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the muggy band about 38% of days. Sticky, muggy-or-worse air turns up on roughly 51% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1102035304
2102035315
391935315
491935325
591935335
691834335
781834346
881734356
981733366
1071633377
1171632377
1261632388
1361531398
1461431409
15514304110
16513294111
17513294212
18512284213
19412284214
20412274215
21411274217
22411264118
23311264119
24311254120
25310254121
26310244122
27210244023
28210244024
29210243925
30210243926
31110243926

Wind in December

Winds average 9 km/h in December.

Across December, daily wind ranges from about 8 km/h on the calmest days to 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
19calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
109calm
119calm
129calm
139calm
149calm
159calm
169calm
179calm
189calm
199calm
209calm
219calm
229calm
239calm
249calm
259calm
269calm
279calm
289calm
299calm
309calm
318calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 13 h 48 min at the start of December to 13 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 6 minutes over December. Sunrise moves from 6:22 AM to 6:32 AM, and sunset from 8:08 PM to 8:25 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.86:228:08
213.86:228:09
313.86:228:10
413.86:228:10
513.86:238:11
613.86:238:12
713.86:238:13
813.86:238:13
913.86:238:14
1013.96:238:15
1113.96:248:15
1213.96:248:16
1313.96:248:17
1413.96:248:17
1513.96:258:18
1613.96:258:18
1713.96:258:19
1813.96:268:19
1913.96:268:20
2013.96:278:20
2113.96:278:21
2213.96:278:21
2313.96:288:22
2413.96:288:22
2513.96:298:23
2613.96:308:23
2713.96:308:24
2813.96:318:24
2913.96:318:24
3013.96:328:25
3113.96:328:25

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 6.44 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 2.41 kWh/m² to a high of 6.44 kWh/m² in December across the year — December's 6.44 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
16.4Intense
26.4Intense
36.4Intense
46.4Intense
56.4Intense
66.4Intense
76.4Intense
86.4Intense
96.4Intense
106.4Intense
116.4Intense
126.4Intense
136.4Intense
146.4Intense
156.4Intense
166.4Intense
176.5Intense
186.5Intense
196.5Intense
206.5Intense
216.5Intense
226.5Intense
236.5Intense
246.4Intense
256.4Intense
266.4Intense
276.4Intense
286.4Intense
296.4Intense
306.4Intense
316.4Intense
Planning a trip in December

Is December a good time to visit São Sebastião do Caí?

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

5.4
Sightseeing
10th-best month of the year
6.1
Beach & pool
1st-best month of the year

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

What to pack for São Sebastião do Caí in December

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

In December, São Sebastião do Caí sees daytime highs around 28°C and nights near 18°C. Pack light clothes, rain gear and sun protection. About 15 days see rain.

light clothesrain gearsun protection

UV index in São Sebastião do Caí in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 13 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in São Sebastião do Caí peaks around January 16 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 20 at about 4 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highModerateHighVery highExtremeJan 16UV 13Jun 20UV 4
UV index (midday)Level
Jan13Extreme
Feb12Extreme
Mar10Very high
Apr8Very high
May5Moderate
Jun4Moderate
Jul4Moderate
Aug5High
Sep8Very high
Oct8Very high
Nov12Extreme
Dec13Extreme

Air quality in São Sebastião do Caí 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 São Sebastião do Caí is worst in September — around 17 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (December, 10 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodSep 1217 µg/m³Dec 1910 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb10Good
Mar10Good
Apr12Good
May12Good
Jun11Good
Jul13Moderate
Aug16Moderate
Sep17Moderate
Oct12Good
Nov11Good
Dec10Good
Location & terrain

Where is São Sebastião do Caí?

São Sebastião do Caí sits at 29.6°S, 51.4°W, 16 m above sea level, in Brazil. The nearest listed city is Montenegro, 14 km away.

Topography around São Sebastião do Caí

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of São Sebastião do Caí.

Within 3 km, the terrain around São Sebastião do Caí has only modest variations in elevation — a maximum elevation change of 107 m around an average of 32 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 512 m; within 80 km, large variations in elevation — a maximum elevation change of 988 m.

The land around São Sebastião do Caí is covered by trees (69%) within 3 km, trees (73%) within 16 km, and trees (62%) within 80 km.

3 km
107 m
16 km
512 m
80 km
988 m
treesgrasslandcroplandartificial surfaceswaterwetland
December weather nearby: Montenegro 14 km · Portão 18 km · Estância Velha 21 km · Ivoti 21 km · Novo Hamburgo 26 km · Dois Irmãos 28 km · São Leopoldo 29 km · Nova Santa Rita 31 km

Brazil travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / N
127 / 220 V · 60 Hz
Prices
≈ 46% of US
price level, 2025
GDP per capita
$10,713
2025
Happiness
6.6 / 10
World Happiness, 2025
Safe drinking water
89%
of population, 2024
Homicide rate
19.3
per 100k, 2023
Road deaths
16
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Low
EF EPI 482
Religion
Roman Catholic 57%Evangelical 27%none 9%other 4%

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 São Sebastião do Caí (-29.5867°, -51.3756°, elevation 16 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. 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).