Rosário weather in December

In December, Rosário sees average daytime highs of 33°C and overnight lows near 25°C, with 98 mm of rain across 15.4 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Day-to-day highs hold fairly steady near 33°C through the month. The sky is clear or mostly clear about 16% of the time in December, and the air most often feels oppressive.

Daylight stretches from about 12 h 12 min at the start of December to 12 h 12 min by month's end. Set against the rest of the year, December is Rosário's 7th-clearest and 4th-windiest month. For the whole year in context, see Rosário's year-round climate.

Daytime high
33°
4th warmest
Overnight low
25°
11th coldest
Rainfall
98 mm
15.4 wet days
Daylight
12 h 12 min
5:48 AM – 5:58 PM
Cloud cover
67%
7th clearest
Wind
11 km/h
4th windiest
Solar energy
5.49 kWh/m²
Travel score
3.0
out of 10

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 33°C through the month.

A typical December day in Rosário reaches about 33°C in the afternoon and slips back to 25°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 31°C and 35°C. Set against its neighbours, December runs on par with November and about 1°C warmer than January.

20°25°30°35°40°151015202531
Avg high (°C)Avg low (°C)
13425
23325
33325
43325
53325
63325
73325
83325
93325
103325
113325
123325
133325
143325
153325
163325
173325
183325
193325
203325
213325
223325
233325
243325
253325
263325
273325
283325
293325
303225
313225

How December really feels in Rosário

Once humidity and wind are folded in, December averages 31 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
31
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

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

Rosário weather by month

How December compares with the rest of the year at a glance. December is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan32° / 24°26225.412.22.6
Feb31° / 24°33025.612.12.5
Mar31° / 24°43730122.4
Apr31° / 24°42628.411.92.5
May31° / 24°25524.111.93.0
Jun31° / 24°9615.711.83.9
Jul31° / 23°579.711.84.5
Aug33° / 24°164.311.94.2
Sep34° / 25°102.6123.6
Oct34° / 25°214.812.13.4
Nov34° / 25°437.112.13.3
Dec33° / 25°9815.412.23.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 16% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 23% of December, with mostly cloudy or overcast conditions the remaining 61%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14951
25050
34951
44951
54951
64951
74951
84852
94852
104753
114654
124456
134456
144357
154258
164060
173862
183763
193565
203466
213367
223268
233268
243070
253070
262971
272872
282773
292773
302674
312575

Chance of precipitation in December

Any precipitation

Rosário gets around 98 mm of rain over 15.4 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 50% and peaks near 69% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)
130
230
331
432
533
634
736
837
938
1040
1141
1243
1345
1446
1548
1650
1752
1854
1956
2057
2159
2260
2361
2462
2563
2664
2766
2866
2967
3068
3169

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 91% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202531
Muggy (%)Oppressive (%)Miserable (%)
14933
24924
34924
44924
53934
63934
73934
83934
93934
102944
112935
122935
132935
141945
151936
161936
171927
181927
191918
201918
211909
2218910
2328810
2428711
2528711
2628612
2728612
2828513
2928513
3018514
3118514

Wind in December

Winds average 11 km/h in December.

Across December, daily wind ranges from about 10 km/h on the calmest days to 12 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
112calm
212calm
312calm
412calm
512calm
612calm
712calm
811calm
911calm
1011calm
1111calm
1211calm
1311calm
1411calm
1511calm
1611calm
1711calm
1811calm
1911calm
2011calm
2111calm
2211calm
2310calm
2410calm
2510calm
2610calm
2710calm
2810calm
2910calm
3010calm
3110calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 12 h 12 min at the start of December to 12 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 5:42 AM to 5:55 AM, and sunset from 5:51 PM to 6:05 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
112.25:425:51
212.25:425:52
312.25:435:52
412.25:435:53
512.25:435:53
612.25:445:54
712.25:445:54
812.25:455:55
912.25:455:55
1012.25:455:55
1112.25:465:56
1212.25:465:56
1312.25:475:57
1412.25:475:57
1512.25:485:58
1612.25:485:58
1712.25:495:59
1812.25:495:59
1912.25:496:00
2012.25:506:00
2112.25:506:01
2212.25:516:01
2312.25:516:02
2412.25:526:02
2512.25:526:02
2612.25:536:03
2712.25:536:03
2812.25:546:04
2912.25:546:04
3012.25:556:05
3112.25:556:05

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 5.49 kWh/m².

For context, solar energy here swings from a low near 4.38 kWh/m² to a high of 6.27 kWh/m² in October across the year — December's 5.49 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.8Bright
25.7Bright
35.7Bright
45.7Bright
55.7Bright
65.7Bright
75.7Bright
85.7Bright
95.6Bright
105.6Bright
115.6Bright
125.6Bright
135.5Bright
145.5Bright
155.5Bright
165.5Bright
175.5Bright
185.4Bright
195.4Bright
205.4Bright
215.3Bright
225.3Bright
235.3Bright
245.3Bright
255.3Bright
265.2Bright
275.2Bright
285.2Bright
295.2Bright
305.2Bright
315.1Bright
Planning a trip in December

Hazard calendar for Rosário

In seasonPeak

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

Rosário's monsoon runs January–May, when most of the year's rain falls.

Monsoon
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is December a good time to visit Rosário?

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

3.0
Sightseeing
7th-best month of the year
5.3
Beach & pool
7th-best month of the year

December is a weaker month for outdoor sightseeing in Rosário.

What to pack for Rosário in December

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

In December, Rosário sees daytime highs around 33°C and nights near 25°C. Pack light clothes and rain gear. Worth having: sun protection. About 15 days see rain.

light clothesrain gearsun protection

Sea temperature near Rosário 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 38 km away) is warmest in May at about 29°C and coldest in October near 28°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
Jan28Tropical
Feb28Tropical
Mar28Tropical
Apr29Tropical
May29Tropical
Jun29Tropical
Jul28Tropical
Aug28Tropical
Sep28Warm
Oct28Warm
Nov28Warm
Dec28Warm

UV index in Rosário in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 11 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Rosário peaks around March 18 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 17 at about 10 (extreme).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeMar 18UV 15Jul 17UV 10
UV index (midday)Level
Jan13Extreme
Feb14Extreme
Mar16Extreme
Apr14Extreme
May11Extreme
Jun10Extreme
Jul10Very high
Aug10Extreme
Sep12Extreme
Oct12Extreme
Nov11Extreme
Dec11Extreme

Air quality in Rosário 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 Rosário is worst in February — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (June, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateFeb 2017 µg/m³Jun 149 µg/m³
PM2.5 (µg/m³)Level
Jan15Moderate
Feb17Moderate
Mar17Moderate
Apr14Moderate
May10Good
Jun9Good
Jul11Good
Aug10Good
Sep10Good
Oct12Moderate
Nov14Moderate
Dec14Moderate
Location & terrain

Where is Rosário?

Rosário sits at 2.9°S, 44.2°W, 1 m above sea level, in Brazil. The nearest listed city is Bacabeira, 8.0 km away.

Topography around Rosário

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

Within 3 km, the terrain around Rosário has only modest variations in elevation — a maximum elevation change of 43 m around an average of 14 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 97 m; within 80 km, only modest variations in elevation — a maximum elevation change of 124 m.

The land around Rosário is covered by trees (57%) and grassland (25%) within 3 km, trees (58%) within 16 km, and trees (44%) within 80 km.

3 km
43 m
16 km
97 m
80 km
124 m
treesshrubsgrasslandartificial surfaceswaterwetlandmangroves
December weather nearby: Bacabeira 8.0 km · Santa Rita 24 km · Morros 25 km · Icatu 27 km · São Luís 46 km · São José de Ribamar 48 km · Paço do Lumiar 48 km · Itapecuru Mirim 52 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 Rosário (-2.9405°, -44.249°, elevation 1 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. 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).