Riachão weather in December

In December, Riachão sees average daytime highs of 30°C and overnight lows near 22°C, with 227 mm of rain across 23.5 wet days and about 12.4 hours of daylight. It is the 9th-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 30°C through the month. The sky is clear or mostly clear about 9% of the time in December, and the air most often feels oppressive.

Daylight stretches from about 12 h 24 min at the start of December to 12 h 24 min by month's end. Set against the rest of the year, December is Riachão's 9th-clearest and 9th-windiest month. For the whole year in context, see Riachão's year-round climate.

Daytime high: 30°; 9th warmest
Overnight low: 22°; 8th coldest
Rainfall: 227 mm; 23.5 wet days
Daylight: 12 h 24 min; 5:50 AM – 6:15 PM
Cloud cover: 77%; 9th clearest
Wind: 6 km/h; 9th windiest
Solar energy: 5.14 kWh/m²
Travel score: 3.3; out of 10

Riachão is settlement in Brazil.

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

← November Riachão year-round climate January →Best places to visit in December

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 30°C through the month.

A typical December day in Riachão reaches about 30°C in the afternoon and slips back to 22°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 27°C and 33°C. Set against its neighbours, December runs on par with November and on par with January.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Avg high (°C)	31	31	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30	30
Avg low (°C)	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22	22

	Avg high (°C)	Avg low (°C)
1	31	22
2	31	22
3	30	22
4	30	22
5	30	22
6	30	22
7	30	22
8	30	22
9	30	22
10	30	22
11	30	22
12	30	22
13	30	22
14	30	22
15	30	22
16	30	22
17	30	22
18	30	22
19	30	22
20	30	22
21	30	22
22	30	22
23	30	22
24	30	22
25	30	22
26	30	22
27	30	22
28	30	22
29	30	22
30	30	22
31	30	22

How December really feels in Riachão

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

heat index over the day's high

Days feeling ≤ 0°C

wind chill below the day's low

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

Riachão weather by month

How December compares with the rest of the year at a glance. December is the 9th-warmest and 4th-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Daylight (hours)	Travel score
Jan	30° / 22°	308	27.2	12.4	3.0
Feb	30° / 22°	268	24.5	12.2	3.0
Mar	30° / 22°	272	26.7	12	3.0
Apr	31° / 22°	149	18.4	11.8	3.7
May	31° / 22°	56	8.6	11.7	4.4
Jun	32° / 22°	4	0.6	11.6	5.0
Jul	33° / 22°	1	0.2	11.6	4.8
Aug	34° / 22°	2	0.4	11.8	4.0
Sep	35° / 23°	16	2.7	12	3.2
Oct	33° / 23°	86	9.9	12.2	3.4
Nov	31° / 22°	185	18.3	12.3	3.5
Dec	30° / 22°	227	23.5	12.4	3.3

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 9% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 14% of December, with mostly cloudy or overcast conditions the remaining 78%.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Clearer (%)	26	27	27	26	26	26	25	25	24	23	23	23	23	23	22	22	22	21	21	21	20	20	20	20	20	20	20	19	19	19	18
Cloudier (%)	74	73	73	74	74	74	75	75	76	77	77	77	77	77	78	78	78	79	79	79	80	80	80	80	80	80	80	81	81	81	82

	Clearer (%)	Cloudier (%)
1	26	74
2	27	73
3	27	73
4	26	74
5	26	74
6	26	74
7	25	75
8	25	75
9	24	76
10	23	77
11	23	77
12	23	77
13	23	77
14	23	77
15	22	78
16	22	78
17	22	78
18	21	79
19	21	79
20	21	79
21	20	80
22	20	80
23	20	80
24	20	80
25	20	80
26	20	80
27	20	80
28	19	81
29	19	81
30	19	81
31	18	82

Chance of precipitation in December

Any precipitation

Riachão gets around 227 mm of rain over 23.5 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 77% and peaks near 84% on the wettest days. The odds climb toward the end of the month.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Rain chance (%)	68	68	68	69	69	70	71	72	73	74	75	76	76	77	77	78	78	79	79	79	79	80	80	81	81	82	82	83	83	84	84

	Rain chance (%)
1	68
2	68
3	68
4	69
5	69
6	70
7	71
8	72
9	73
10	74
11	75
12	76
13	76
14	77
15	77
16	78
17	78
18	79
19	79
20	79
21	79
22	80
23	80
24	81
25	81
26	82
27	82
28	83
29	83
30	84
31	84

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 87% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Muggy (%)	16	16	16	15	15	15	14	14	13	13	12	12	12	12	12	12	12	12	12	12	12	12	12	12	11	11	11	11	10	10	10
Oppressive (%)	84	84	84	85	85	85	86	86	87	87	88	88	88	88	88	88	88	88	88	88	88	88	88	88	89	89	89	89	90	90	90

	Muggy (%)	Oppressive (%)
1	16	84
2	16	84
3	16	84
4	15	85
5	15	85
6	15	85
7	14	86
8	14	86
9	13	87
10	13	87
11	12	88
12	12	88
13	12	88
14	12	88
15	12	88
16	12	88
17	12	88
18	12	88
19	12	88
20	12	88
21	12	88
22	12	88
23	12	88
24	12	88
25	11	89
26	11	89
27	11	89
28	11	89
29	10	90
30	10	90
31	10	90

Wind in December

Winds average 6 km/h in December.

Across December, daily wind ranges from about 6 km/h on the calmest days to 6 km/h at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Wind speed (km/h)	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6	6
Feels	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm

	Wind speed (km/h)	Feels
1	6	calm
2	6	calm
3	6	calm
4	6	calm
5	6	calm
6	6	calm
7	6	calm
8	6	calm
9	6	calm
10	6	calm
11	6	calm
12	6	calm
13	6	calm
14	6	calm
15	6	calm
16	6	calm
17	6	calm
18	6	calm
19	6	calm
20	6	calm
21	6	calm
22	6	calm
23	6	calm
24	6	calm
25	6	calm
26	6	calm
27	6	calm
28	6	calm
29	6	calm
30	6	calm
31	6	calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 12 h 24 min at the start of December to 12 h 24 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 5:44 AM to 5:57 AM, and sunset from 6:08 PM to 6:22 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Daylight (h)	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4	12.4
Sunrise (AM)	5:44	5:45	5:45	5:45	5:46	5:46	5:46	5:47	5:47	5:47	5:48	5:48	5:49	5:49	5:49	5:50	5:50	5:51	5:51	5:52	5:52	5:53	5:53	5:54	5:54	5:55	5:55	5:55	5:56	5:56	5:57
Sunset (PM)	6:08	6:09	6:09	6:10	6:10	6:11	6:11	6:11	6:12	6:12	6:13	6:13	6:14	6:14	6:15	6:15	6:16	6:16	6:17	6:17	6:18	6:18	6:19	6:19	6:20	6:20	6:21	6:21	6:21	6:22	6:22

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	12.4	5:44	6:08
2	12.4	5:45	6:09
3	12.4	5:45	6:09
4	12.4	5:45	6:10
5	12.4	5:46	6:10
6	12.4	5:46	6:11
7	12.4	5:46	6:11
8	12.4	5:47	6:11
9	12.4	5:47	6:12
10	12.4	5:47	6:12
11	12.4	5:48	6:13
12	12.4	5:48	6:13
13	12.4	5:49	6:14
14	12.4	5:49	6:14
15	12.4	5:49	6:15
16	12.4	5:50	6:15
17	12.4	5:50	6:16
18	12.4	5:51	6:16
19	12.4	5:51	6:17
20	12.4	5:52	6:17
21	12.4	5:52	6:18
22	12.4	5:53	6:18
23	12.4	5:53	6:19
24	12.4	5:54	6:19
25	12.4	5:54	6:20
26	12.4	5:55	6:20
27	12.4	5:55	6:21
28	12.4	5:55	6:21
29	12.4	5:56	6:21
30	12.4	5:56	6:22
31	12.4	5:57	6:22

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 5.14 kWh/m².

For context, solar energy here swings from a low near 4.88 kWh/m² to a high of 6.55 kWh/m² in September across the year — December's 5.14 kWh/m² falls in the middle.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Solar energy (kWh/m²)	5.3	5.3	5.3	5.3	5.3	5.3	5.2	5.2	5.2	5.2	5.2	5.2	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.1	5.0	5.0	5.0	5.0	5.0	5.0	5.0	5.0	5.0	5.0	5.0
Level	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright

	Solar energy (kWh/m²)	Level
1	5.3	Bright
2	5.3	Bright
3	5.3	Bright
4	5.3	Bright
5	5.3	Bright
6	5.3	Bright
7	5.2	Bright
8	5.2	Bright
9	5.2	Bright
10	5.2	Bright
11	5.2	Bright
12	5.2	Bright
13	5.1	Bright
14	5.1	Bright
15	5.1	Bright
16	5.1	Bright
17	5.1	Bright
18	5.1	Bright
19	5.1	Bright
20	5.1	Bright
21	5.0	Bright
22	5.0	Bright
23	5.0	Bright
24	5.0	Bright
25	5.0	Bright
26	5.0	Bright
27	5.0	Bright
28	5.0	Bright
29	5.0	Bright
30	5.0	Bright
31	5.0	Bright

Planning a trip in December

Hazard calendar for Riachão

In seasonPeak

In December, Riachão sits inside its monsoon season. The full year is below, with each hazard's peak months called out.

Riachão's monsoon runs November–April, 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 Riachão?

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

3.3

Sightseeing

8th-best month of the year

4.5

Beach & pool

9th-best month of the year

December is a weaker month for outdoor sightseeing in Riachão.

What to pack for Riachão in December

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

In December, Riachão sees daytime highs around 30°C and nights near 22°C. Pack light clothes and rain gear. Worth having: sun protection. About 24 days see rain.

light clothesrain gearsun protection

UV index in Riachão 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 Riachão peaks around February 21 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 22 at about 10 (very high).

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

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	14	15	15	14	11	10	10	11	12	12	12	11
Level	Extreme	Extreme	Extreme	Extreme	Extreme	Very high	Very high	Extreme	Extreme	Extreme	Extreme	Extreme

	UV index (midday)	Level
Jan	14	Extreme
Feb	15	Extreme
Mar	15	Extreme
Apr	14	Extreme
May	11	Extreme
Jun	10	Very high
Jul	10	Very high
Aug	11	Extreme
Sep	12	Extreme
Oct	12	Extreme
Nov	12	Extreme
Dec	11	Extreme

Air quality in Riachão 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 Riachão is worst in September — around 30 µg/m³ PM2.5 (moderate), about 5.1× the cleanest month (June, 6 µg/m³).

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

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
PM2.5 (µg/m³)	12	11	11	11	7	6	7	15	30	26	17	14
Level	Good	Good	Good	Good	Good	Good	Good	Moderate	Moderate	Moderate	Moderate	Moderate

	PM2.5 (µg/m³)	Level
Jan	12	Good
Feb	11	Good
Mar	11	Good
Apr	11	Good
May	7	Good
Jun	6	Good
Jul	7	Good
Aug	15	Moderate
Sep	30	Moderate
Oct	26	Moderate
Nov	17	Moderate
Dec	14	Moderate

Location & terrain

Where is Riachão?

Riachão sits at 7.4°S, 46.6°W, 385 m above sea level, in Brazil. The nearest listed city is Balsas, 67 km away.

Topography around Riachão

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

Within 3 km, the terrain around Riachão has only modest variations in elevation — a maximum elevation change of 80 m around an average of 378 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 374 m; within 80 km, significant variations in elevation — a maximum elevation change of 475 m.

The land around Riachão is covered by grassland (47%), trees (25%) and shrubs (20%) within 3 km, grassland (45%), trees (33%) and shrubs (21%) within 16 km, and trees (36%), grassland (36%) and shrubs (20%) within 80 km.

3 km

80 m

grassland 47%

16 km

374 m

grassland 45%

80 km

475 m

trees 36%

treesshrubsgrasslandcroplandartificial surfaces

← November Riachão year-round climate January →Best places to visit in December

December weather nearby: Balsas 67 km · Carolina 93 km · Formosa da Serra Negra 112 km · Estreito 128 km · São Raimundo das Mangabeiras 131 km · Porto Franco 143 km · Tocantinópolis 145 km · Sítio Novo 165 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

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 Riachão (-7.3619°, -46.6172°, elevation 385 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).

	Avg high (°C)	Avg low (°C)
1	31	22
2	31	22
3	30	22
4	30	22
5	30	22
6	30	22
7	30	22
8	30	22
9	30	22
10	30	22
11	30	22
12	30	22
13	30	22
14	30	22
15	30	22
16	30	22
17	30	22
18	30	22
19	30	22
20	30	22
21	30	22
22	30	22
23	30	22
24	30	22
25	30	22
26	30	22
27	30	22
28	30	22
29	30	22
30	30	22
31	30	22

	Clearer (%)	Cloudier (%)
1	26	74
2	27	73
3	27	73
4	26	74
5	26	74
6	26	74
7	25	75
8	25	75
9	24	76
10	23	77
11	23	77
12	23	77
13	23	77
14	23	77
15	22	78
16	22	78
17	22	78
18	21	79
19	21	79
20	21	79
21	20	80
22	20	80
23	20	80
24	20	80
25	20	80
26	20	80
27	20	80
28	19	81
29	19	81
30	19	81
31	18	82

	Rain chance (%)
1	68
2	68
3	68
4	69
5	69
6	70
7	71
8	72
9	73
10	74
11	75
12	76
13	76
14	77
15	77
16	78
17	78
18	79
19	79
20	79
21	79
22	80
23	80
24	81
25	81
26	82
27	82
28	83
29	83
30	84
31	84

	Muggy (%)	Oppressive (%)
1	16	84
2	16	84
3	16	84
4	15	85
5	15	85
6	15	85
7	14	86
8	14	86
9	13	87
10	13	87
11	12	88
12	12	88
13	12	88
14	12	88
15	12	88
16	12	88
17	12	88
18	12	88
19	12	88
20	12	88
21	12	88
22	12	88
23	12	88
24	12	88
25	11	89
26	11	89
27	11	89
28	11	89
29	10	90
30	10	90
31	10	90

	Avg high (°C)	Avg low (°C)
1	31	22
2	31	22
3	30	22
4	30	22
5	30	22
6	30	22
7	30	22
8	30	22
9	30	22
10	30	22
11	30	22
12	30	22
13	30	22
14	30	22
15	30	22
16	30	22
17	30	22
18	30	22
19	30	22
20	30	22
21	30	22
22	30	22
23	30	22
24	30	22
25	30	22
26	30	22
27	30	22
28	30	22
29	30	22
30	30	22
31	30	22

	Clearer (%)	Cloudier (%)
1	26	74
2	27	73
3	27	73
4	26	74
5	26	74
6	26	74
7	25	75
8	25	75
9	24	76
10	23	77
11	23	77
12	23	77
13	23	77
14	23	77
15	22	78
16	22	78
17	22	78
18	21	79
19	21	79
20	21	79
21	20	80
22	20	80
23	20	80
24	20	80
25	20	80
26	20	80
27	20	80
28	19	81
29	19	81
30	19	81
31	18	82

	Rain chance (%)
1	68
2	68
3	68
4	69
5	69
6	70
7	71
8	72
9	73
10	74
11	75
12	76
13	76
14	77
15	77
16	78
17	78
18	79
19	79
20	79
21	79
22	80
23	80
24	81
25	81
26	82
27	82
28	83
29	83
30	84
31	84

	Muggy (%)	Oppressive (%)
1	16	84
2	16	84
3	16	84
4	15	85
5	15	85
6	15	85
7	14	86
8	14	86
9	13	87
10	13	87
11	12	88
12	12	88
13	12	88
14	12	88
15	12	88
16	12	88
17	12	88
18	12	88
19	12	88
20	12	88
21	12	88
22	12	88
23	12	88
24	12	88
25	11	89
26	11	89
27	11	89
28	11	89
29	10	90
30	10	90
31	10	90

	Avg high (°C)	Avg low (°C)
1	31	22
2	31	22
3	30	22
4	30	22
5	30	22
6	30	22
7	30	22
8	30	22
9	30	22
10	30	22
11	30	22
12	30	22
13	30	22
14	30	22
15	30	22
16	30	22
17	30	22
18	30	22
19	30	22
20	30	22
21	30	22
22	30	22
23	30	22
24	30	22
25	30	22
26	30	22
27	30	22
28	30	22
29	30	22
30	30	22
31	30	22

	Clearer (%)	Cloudier (%)
1	26	74
2	27	73
3	27	73
4	26	74
5	26	74
6	26	74
7	25	75
8	25	75
9	24	76
10	23	77
11	23	77
12	23	77
13	23	77
14	23	77
15	22	78
16	22	78
17	22	78
18	21	79
19	21	79
20	21	79
21	20	80
22	20	80
23	20	80
24	20	80
25	20	80
26	20	80
27	20	80
28	19	81
29	19	81
30	19	81
31	18	82

	Rain chance (%)
1	68
2	68
3	68
4	69
5	69
6	70
7	71
8	72
9	73
10	74
11	75
12	76
13	76
14	77
15	77
16	78
17	78
18	79
19	79
20	79
21	79
22	80
23	80
24	81
25	81
26	82
27	82
28	83
29	83
30	84
31	84

	Muggy (%)	Oppressive (%)
1	16	84
2	16	84
3	16	84
4	15	85
5	15	85
6	15	85
7	14	86
8	14	86
9	13	87
10	13	87
11	12	88
12	12	88
13	12	88
14	12	88
15	12	88
16	12	88
17	12	88
18	12	88
19	12	88
20	12	88
21	12	88
22	12	88
23	12	88
24	12	88
25	11	89
26	11	89
27	11	89
28	11	89
29	10	90
30	10	90
31	10	90