Rio Negro weather in December

In December, Rio Negro sees average daytime highs of 26°C and overnight lows near 17°C, with 149 mm of rain across 17 wet days and about 13.6 hours of daylight. It is the 3rd-warmest and 3rd-wettest month of the year here.

Day-to-day highs hold fairly steady near 26°C through the month. The sky is clear or mostly clear about 15% of the time in December, and the air most often feels humid.

Daylight stretches from about 13 h 30 min at the start of December to 13 h 36 min by month's end. Set against the rest of the year, December is Rio Negro's 10th-clearest and 4th-windiest month. For the whole year in context, see Rio Negro's year-round climate.

Daytime high
26°
3rd warmest
Overnight low
17°
10th coldest
Rainfall
149 mm
17 wet days
Daylight
13 h 36 min
6:27 AM – 8:04 PM
Cloud cover
73%
10th clearest
Wind
10 km/h
4th windiest
Solar energy
5.66 kWh/m²
Travel score
5.4
out of 10

Rio Negro is settlement in Brazil.

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 26°C through the month.

A typical December day in Rio Negro reaches about 26°C in the afternoon and slips back to 17°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 30°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)
12616
22616
32616
42616
52616
62617
72617
82617
92617
102617
112617
122617
132617
142617
152617
162617
172617
182617
192617
202717
212717
222717
232718
242718
252718
262718
272718
282718
292718
302718
312718

Rio Negro 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
Jan27° / 18°18319.913.54.9
Feb27° / 18°15717.812.95.0
Mar26° / 17°10614.212.25.9
Apr24° / 15°718.811.46.9
May21° / 12°94810.76.6
Jun19° / 10°1069.210.46.3
Jul19° / 86810.56.5
Aug21° / 10°847.811.17.0
Sep22° / 12°14510.811.86.4
Oct23° / 14°14414.212.66.0
Nov25° / 15°12313.913.36.0
Dec26° / 17°1491713.65.4

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 15% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 15% of December, with mostly cloudy or overcast conditions the remaining 71%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13268
23268
33268
43169
53070
62971
72971
82971
92971
102971
112971
122971
132971
142971
152971
163070
173070
182971
192971
203070
213070
223070
233070
243070
252971
262872
272872
282872
292773
302773
312773

Chance of precipitation in December

Any precipitation

Rio Negro gets around 149 mm of rain over 17 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 56% and peaks near 61% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%151015202531
Rain chance (%)
150
250
351
451
551
652
752
853
953
1054
1154
1255
1355
1455
1556
1656
1756
1856
1957
2057
2157
2257
2358
2458
2558
2659
2759
2860
2960
3061
3161

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the humid band about 39% of days. Sticky, muggy-or-worse air turns up on roughly 35% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
111274220
210264221
310264322
49254323
59244324
69244324
79234325
89224326
98224327
108214328
118214329
128204330
137194231
147194232
157184233
167184134
176184135
186174037
196173938
205173839
215173741
224173642
234173643
243173545
253173446
262173347
272173348
282173248
292173249
301173250
311173250

Wind in December

Winds average 10 km/h in December.

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

051015151015202531
Wind speed (km/h)Feels
110calm
210calm
310calm
410calm
510calm
610calm
710calm
810calm
910calm
1010calm
1110calm
1210calm
1310calm
1410calm
1510calm
1610calm
1710calm
1810calm
1910calm
2010calm
2110calm
2210calm
2310calm
2410calm
2510calm
2610calm
2710calm
2810calm
2910calm
3010calm
3110calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 13 h 30 min at the start of December to 13 h 36 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 6:23 AM to 6:34 AM, and sunset from 7:54 PM to 8:11 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.56:237:54
213.56:237:55
313.56:247:56
413.56:247:57
513.66:247:57
613.66:247:58
713.66:247:59
813.66:247:59
913.66:258:00
1013.66:258:01
1113.66:258:01
1213.66:258:02
1313.66:268:02
1413.66:268:03
1513.66:268:04
1613.66:278:04
1713.66:278:05
1813.66:278:05
1913.66:288:06
2013.66:288:06
2113.66:298:07
2213.66:298:07
2313.66:308:08
2413.66:308:08
2513.66:318:09
2613.66:318:09
2713.66:328:09
2813.66:328:10
2913.66:338:10
3013.66:338:10
3113.66:348:11

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 5.66 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 2.77 kWh/m² to a high of 5.66 kWh/m² in December across the year — December's 5.66 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.6Bright
25.6Bright
35.6Bright
45.6Bright
55.6Bright
65.6Bright
75.6Bright
85.6Bright
95.6Bright
105.6Bright
115.6Bright
125.6Bright
135.6Bright
145.6Bright
155.6Bright
165.7Bright
175.7Bright
185.7Bright
195.7Bright
205.7Bright
215.7Bright
225.7Bright
235.7Bright
245.7Bright
255.7Bright
265.7Bright
275.7Bright
285.7Bright
295.7Bright
305.6Bright
315.6Bright
Planning a trip in December

Is December a good time to visit Rio Negro?

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
5.3
Beach & pool
4th-best month of the year

December is a reasonable time to visit Rio Negro for sightseeing.

What to pack for Rio Negro in December

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

In December, Rio Negro sees daytime highs around 26°C and nights near 17°C. Pack rain gear. Worth having: light clothes and sun protection. About 17 days see rain.

rain gearlight clothessun protection

UV index in Rio Negro in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 14 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Rio Negro peaks around January 19 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 12 at about 5 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighVery highExtremeJan 19UV 15Jul 12UV 5
UV index (midday)Level
Jan15Extreme
Feb14Extreme
Mar12Extreme
Apr9Very high
May6High
Jun6High
Jul5High
Aug7High
Sep8Very high
Oct11Extreme
Nov13Extreme
Dec14Extreme

Air quality in Rio Negro 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 Rio Negro is worst in September — around 16 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (February, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodSep 1115 µg/m³Feb 139 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb9Good
Mar9Good
Apr11Good
May12Moderate
Jun12Good
Jul14Moderate
Aug15Moderate
Sep16Moderate
Oct11Good
Nov10Good
Dec9Good
Location & terrain

Where is Rio Negro?

Rio Negro sits at 26.1°S, 49.8°W, 795 m above sea level, in Brazil. The nearest listed city is Mafra, 1.0 km away.

Topography around Rio Negro

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

Within 3 km, the terrain around Rio Negro has only modest variations in elevation — a maximum elevation change of 110 m around an average of 800 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 196 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,275 m.

The land around Rio Negro is covered by trees (43%) and artificial surfaces (38%) within 3 km, trees (58%) and cropland (30%) within 16 km, and trees (68%) and cropland (23%) within 80 km.

3 km
110 m
16 km
196 m
80 km
1,275 m
treesgrasslandcroplandartificial surfaceswater
December weather nearby: Mafra 1.0 km · Itaiópolis 28 km · Rio Negrinho 32 km · Lapa 38 km · Quitandinha 40 km · São Bento do Sul 45 km · Papanduva 45 km · Três Barras 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 Rio Negro (-26.1058°, -49.7975°, elevation 795 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).