Rio Branco weather in May

In May, Rio Branco sees average daytime highs of 30°C and overnight lows near 21°C, with 76 mm of rain across 15.4 wet days and about 11.5 hours of daylight. It is the 12th-warmest and 8th-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 15% of the time in May, and the air most often feels oppressive.

Daylight stretches from about 11 h 42 min at the start of May to 11 h 30 min by month's end. Set against the rest of the year, May is Rio Branco's 5th-clearest and 10th-windiest month. For the whole year in context, see Rio Branco's year-round climate.

Daytime high
30°
12th warmest
Overnight low
21°
4th coldest
Rainfall
76 mm
15.4 wet days
Daylight
11 h 30 min
5:41 AM – 5:14 PM
Cloud cover
69%
5th clearest
Wind
6 km/h
10th windiest
Solar energy
4.25 kWh/m²
Travel score
4.3
out of 10

Rio Branco is human settlement in Acre, Brazil.

Founded
1882

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

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

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

A typical May day in Rio Branco reaches about 30°C in the afternoon and slips back to 21°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 26°C and 32°C. Set against its neighbours, May runs on par with April and on par with June.

15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
13022
23022
33022
43022
53022
63022
73022
83022
93022
103022
113022
123022
133022
143022
153021
163021
173021
183021
193021
203021
213021
223021
233021
243021
253021
263021
273021
283021
293021
303021
313021

How May really feels in Rio Branco

Once humidity and wind are folded in, May 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 May is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Rio Branco weather by month

How May compares with the rest of the year at a glance. May is the 12th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan30° / 23°25527.712.52.8
Feb30° / 23°2402512.32.8
Mar30° / 23°24927.212.12.8
Apr30° / 22°16022.811.83.2
May30° / 21°7615.411.54.3
Jun30° / 20°306.811.45.3
Jul31° / 20°214.211.55.1
Aug33° / 20°386.311.74.0
Sep33° / 22°7611.911.93.2
Oct33° / 23°13719.512.22.8
Nov31° / 23°19922.912.52.8
Dec30° / 23°24626.312.62.9

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

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

Beyond those clear spells, partly cloudy skies cover about 18% of May, with mostly cloudy or overcast conditions the remaining 67%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
12278
22377
32377
42476
52575
62674
72773
82872
92872
102971
112971
122971
133169
143169
153367
163367
173466
183466
193565
203565
213664
223763
233862
243961
254060
264159
274159
284258
294456
304555
314654

Chance of precipitation in May

Any precipitation

Rio Branco gets around 76 mm of rain over 15.4 wet days in May. 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 63% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202531
Rain chance (%)
163
262
361
460
559
658
757
856
956
1055
1154
1254
1353
1452
1552
1651
1750
1849
1948
2047
2146
2245
2344
2443
2542
2641
2741
2840
2939
3038
3137

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the oppressive band about 57% of days. Sticky, muggy-or-worse air turns up on roughly 93% of them.

0%25%50%75%100%151015202531
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
11495333
22495332
32495431
424105430
524105529
634105429
734115428
834115428
934115527
1034115527
1134125526
1234125526
1334125526
1434135525
1534135525
1634135525
1734145524
1834145524
1934155523
2034155622
2124155821
2224165820
2324165919
2424176017
2524176116
2624176215
2724176314
2824186313
2925186312
3025186411
3125186510

Wind in May

Winds average 6 km/h in May.

Across May, daily wind ranges from about 5 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
15calm
25calm
35calm
45calm
55calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm
315calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 11 h 42 min at the start of May to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over May. Sunrise moves from 5:39 AM to 5:45 AM, and sunset from 5:18 PM to 5:13 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
111.75:395:18
211.65:395:18
311.65:395:17
411.65:395:17
511.65:395:17
611.65:395:16
711.65:405:16
811.65:405:16
911.65:405:15
1011.65:405:15
1111.65:405:15
1211.65:405:15
1311.65:415:14
1411.65:415:14
1511.65:415:14
1611.55:415:14
1711.55:415:14
1811.55:425:13
1911.55:425:13
2011.55:425:13
2111.55:425:13
2211.55:425:13
2311.55:435:13
2411.55:435:13
2511.55:435:13
2611.55:435:13
2711.55:445:13
2811.55:445:13
2911.55:445:13
3011.55:445:13
3111.55:455:13

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 4.25 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 4.25 kWh/m² to a high of 5.57 kWh/m² in September across the year — May's 4.25 kWh/m² sits near the bottom.

012345151015202531
Solar energy (kWh/m²)Level
14.3Bright
24.3Bright
34.3Bright
44.3Bright
54.3Bright
64.3Bright
74.3Bright
84.3Bright
94.3Bright
104.3Bright
114.3Bright
124.3Bright
134.3Bright
144.3Bright
154.3Bright
164.3Bright
174.2Bright
184.2Bright
194.2Bright
204.2Bright
214.2Bright
224.2Bright
234.2Bright
244.2Bright
254.2Bright
264.2Bright
274.2Bright
284.2Bright
294.2Bright
304.2Bright
314.2Bright
Planning a trip in May

Hazard calendar for Rio Branco

In seasonPeak

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

Rio Branco's rainy season runs October–April, when most of the year's rain falls.

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

Is May a good time to visit Rio Branco?

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

4.3
Sightseeing
3rd-best month of the year
5.9
Beach & pool
4th-best month of the year

May is a reasonable time to visit Rio Branco for sightseeing.

What to pack for Rio Branco in May

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

In May, Rio Branco sees daytime highs around 30°C and nights near 21°C. Pack light clothes and rain gear. About 15 days see rain.

light clothesrain gear

UV index in Rio Branco in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May 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 Rio Branco peaks around January 20 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near September 12 at about 5 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighExtremeJan 20UV 15Sep 12UV 5
UV index (midday)Level
Jan15Extreme
Feb15Extreme
Mar14Extreme
Apr13Extreme
May11Extreme
Jun9Very high
Jul8Very high
Aug7High
Sep4Moderate
Oct12Extreme
Nov13Extreme
Dec13Extreme

Air quality in Rio Branco in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in Rio Branco is worst in September — around 100 µg/m³ PM2.5 (unhealthy), about 12.4× the cleanest month (June, 8 µg/m³).

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

0306090120JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateUnhealthyModerateGoodSep 1394 µg/m³Jun 98 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar13Moderate
Apr10Good
May8Good
Jun8Good
Jul14Moderate
Aug65Unhealthy
Sep100Unhealthy
Oct27Moderate
Nov13Moderate
Dec11Good
Location & terrain

Where is Rio Branco?

Rio Branco sits at 10.0°S, 67.8°W, 153 m above sea level, in Brazil. The nearest listed city is Senador Guiomard, 21 km away.

Topography around Rio Branco

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

Within 3 km, the terrain around Rio Branco has only modest variations in elevation — a maximum elevation change of 50 m around an average of 142 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 103 m; within 80 km, only modest variations in elevation — a maximum elevation change of 165 m.

The land around Rio Branco is covered by artificial surfaces (54%) and trees (33%) within 3 km, trees (46%) and grassland (46%) within 16 km, and trees (61%) and grassland (38%) within 80 km.

3 km
50 m
16 km
103 m
80 km
165 m
treesgrasslandartificial surfaceswater
May weather nearby: Senador Guiomard 21 km · Porto Acre 53 km · Plácido de Castro 79 km · Xapuri 107 km · Sena Madureira 139 km · Boca do Acre 143 km · Brasiléia 155 km · Epitaciolândia 155 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 Branco (-9.9747°, -67.81°, elevation 153 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).