Grajaú weather in December

In December, Grajaú sees average daytime highs of 32°C and overnight lows near 23°C, with 135 mm of rain across 17.7 wet days and about 12.3 hours of daylight. It is the 7th-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 32°C through the month. The sky is clear or mostly clear about 11% of the time in December, and the air most often feels oppressive.

Daylight stretches from about 12 h 18 min at the start of December to 12 h 18 min by month's end. Set against the rest of the year, December is Grajaú's 8th-clearest and 8th-windiest month. For the whole year in context, see Grajaú's year-round climate.

Daytime high
32°
7th warmest
Overnight low
23°
10th coldest
Rainfall
135 mm
17.7 wet days
Daylight
12 h 18 min
5:51 AM – 6:11 PM
Cloud cover
74%
8th clearest
Wind
6 km/h
8th windiest
Solar energy
5.09 kWh/m²
Travel score
3.3
out of 10

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 32°C through the month.

A typical December day in Grajaú reaches about 32°C in the afternoon and slips back to 23°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 29°C and 34°C. Set against its neighbours, December runs about 1°C cooler than November and about 1°C warmer than January.

20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
13223
23223
33223
43223
53223
63223
73223
83223
93223
103223
113223
123223
133223
143223
153223
163223
173223
183123
193123
203123
213123
223123
233123
243123
253123
263123
273123
283123
293123
303123
313123

How December really feels in Grajaú

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.

Grajaú weather by month

How December compares with the rest of the year at a glance. December is the 7th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan31° / 23°17224.812.33.0
Feb30° / 22°17523.912.22.9
Mar31° / 23°18826.1122.9
Apr31° / 23°13220.411.93.3
May31° / 22°6410.511.74.2
Jun32° / 22°81.611.74.8
Jul33° / 21°50.811.74.4
Aug34° / 22°20.311.83.8
Sep35° / 23°91.7123.4
Oct34° / 24°325.312.13.4
Nov33° / 24°7811.912.33.4
Dec32° / 23°13517.712.33.3

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 11% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 16% of December, with mostly cloudy or overcast conditions the remaining 73%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13466
23466
33466
43466
53466
63466
73466
83466
93367
103367
113268
123070
133070
142872
152773
162773
172575
182575
192476
202377
212278
222278
232278
242080
252080
262080
272080
281981
291981
301882
311783

Chance of precipitation in December

Any precipitation

Grajaú gets around 135 mm of rain over 17.7 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 58% and peaks near 73% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)
145
245
345
445
546
646
747
848
949
1050
1151
1252
1354
1455
1557
1658
1760
1861
1962
2064
2165
2266
2367
2468
2569
2669
2770
2871
2972
3072
3173

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 94% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202531
Muggy (%)Oppressive (%)Miserable (%)
112880
212880
311890
411890
511890
610900
79910
89910
98920
107930
117930
126940
135950
145950
154960
164960
173961
183961
193961
202971
212971
222971
232971
242962
251972
261972
271972
281972
291972
301972
311972

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.

0246810151015202531
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 12 h 18 min at the start of December to 12 h 18 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 5:45 AM to 5:58 AM, and sunset from 6:04 PM to 6:18 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
112.35:456:04
212.35:456:04
312.35:466:05
412.35:466:05
512.35:466:06
612.35:476:06
712.35:476:06
812.35:476:07
912.35:486:07
1012.35:486:08
1112.35:496:08
1212.35:496:09
1312.35:496:09
1412.35:506:10
1512.35:506:10
1612.35:516:11
1712.35:516:11
1812.35:526:12
1912.35:526:12
2012.35:526:13
2112.35:536:13
2212.35:536:14
2312.35:546:14
2412.35:546:15
2512.35:556:15
2612.35:556:16
2712.35:566:16
2812.35:566:16
2912.35:576:17
3012.35:576:17
3112.35:586:18

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 5.09 kWh/m².

For context, solar energy here swings from a low near 4.51 kWh/m² to a high of 6.39 kWh/m² in September across the year — December's 5.09 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.3Bright
45.3Bright
55.3Bright
65.3Bright
75.3Bright
85.3Bright
95.2Bright
105.2Bright
115.2Bright
125.2Bright
135.1Bright
145.1Bright
155.1Bright
165.0Bright
175.0Bright
185.0Bright
195.0Bright
205.0Bright
214.9Bright
224.9Bright
234.9Bright
244.9Bright
254.8Bright
264.8Bright
274.8Bright
284.8Bright
294.8Bright
304.8Bright
314.8Bright
Planning a trip in December

Hazard calendar for Grajaú

In seasonPeak

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

Grajaú's monsoon runs December–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 Grajaú?

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
5.1
Beach & pool
8th-best month of the year

December is a weaker month for outdoor sightseeing in Grajaú.

What to pack for Grajaú in December

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

In December, Grajaú sees daytime highs around 32°C and nights near 23°C. Pack light clothes and rain gear. Worth having: sun protection. About 18 days see rain.

light clothesrain gearsun protection

UV index in Grajaú in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Grajaú peaks around March 12 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 12 at about 10 (extreme).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeMar 12UV 15Jul 12UV 10
UV index (midday)Level
Jan14Extreme
Feb15Extreme
Mar15Extreme
Apr14Extreme
May11Extreme
Jun10Extreme
Jul10Very high
Aug11Extreme
Sep12Extreme
Oct12Extreme
Nov12Extreme
Dec10Extreme

Air quality in Grajaú 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 Grajaú is worst in October — around 28 µg/m³ PM2.5 (moderate), about 4.5× the cleanest month (June, 6 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateOct 1227 µg/m³Jun 176 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb12Good
Mar12Good
Apr11Good
May9Good
Jun6Good
Jul8Good
Aug17Moderate
Sep26Moderate
Oct28Moderate
Nov22Moderate
Dec17Moderate
Location & terrain

Where is Grajaú?

Grajaú sits at 5.8°S, 46.1°W, 163 m above sea level, in Brazil. The nearest listed city is Sítio Novo, 62 km away.

Topography around Grajaú

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

Within 3 km, the terrain around Grajaú has only modest variations in elevation — a maximum elevation change of 115 m around an average of 193 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 218 m; within 80 km, significant variations in elevation — a maximum elevation change of 593 m.

The land around Grajaú is covered by trees (53%), grassland (24%) and artificial surfaces (20%) within 3 km, trees (58%) and grassland (33%) within 16 km, and trees (66%) and grassland (26%) within 80 km.

3 km
115 m
16 km
218 m
80 km
593 m
treesshrubsgrasslandcroplandartificial surfaces
December weather nearby: Sítio Novo 62 km · Formosa da Serra Negra 70 km · Amarante do Maranhão 72 km · Jenipapo dos Vieiras 75 km · Arame 105 km · Barra do Corda 105 km · Governador Edison Lobão 136 km · João Lisboa 146 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 Grajaú (-5.8194°, -46.1386°, elevation 163 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).