Climate and average weather in Guajará Mirim

In Guajará Mirim, the weather is muggy, sweltering, wet, and partly cloudy and remarkably steady, with daytime highs holding near sweltering levels all year. The wettest stretch peaks around January.

Best: mid May to early August

Over the course of the year, the temperature in Guajará Mirim typically varies from 20°C to 33°C, and is rarely below 16°C or above 36°C. September is the hottest month of the year, while May is the coldest.

Based on the travel score, the best time of year to visit Guajará Mirim for warm-weather activities is from mid May to early August.

Hottest
Sep
33°
Coldest
May
22°
Wettest
Jan
265 mm
Driest
Jul
21 mm
Rain / yr
1820 mm
220 wet days
Daylight
11.4–12.6 h
shortest–longest
Elevation
131 m
10.8°S
Clearest
Jul
34% cloud

Guajará Mirim weather by month, at a glance

The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.

Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around mid May to early August.

Temperature through the year

Average highAverage lowShaded bands: 10–90% of days

Daily average highs and lows in Guajará Mirim, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.

Temperatures in Guajará Mirim stay fairly even through the year, without a distinct hot or cool season. The warmest month is September, with an average high of 33°C and low of 22°C; the coolest is May, with an average low of 22°C and high of 30°C.

Days typically run about 9°C warmer than nights, with the widest day–night swing (around 12°C) in August.

15°20°25°30°35°40°JanFebMarAprMayJunJulAugSepOctNovDec
Avg high (°C)Avg low (°C)
Jan3023
Feb3023
Mar3023
Apr3023
May3022
Jun3021
Jul3120
Aug3321
Sep3322
Oct3323
Nov3123
Dec3123

How hot and cold Guajará Mirim really feels

Feels-like highFeels-like lowactual air temp

The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.

On the hottest afternoons, once humidity is folded in, Guajará Mirim feels like about 38°C (around October 13). Nearly every day a year carries some heat stress, peaking in October.

15°20°25°30°35°40°JanFebMarAprMayJunJulAugSepOctNovDecdangerous heat
Feels-like high (°C)Air high (°C)Feels-like low (°C)Air low (°C)
Jan35302323
Feb35302323
Mar36302323
Apr36302323
May34302222
Jun33302121
Jul33312020
Aug35332121
Sep37332222
Oct38332323
Nov37312323
Dec36312323

Average hourly temperature in Guajará Mirim

A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.

Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on September afternoons, near 33°C, and coldest before dawn in May, near 22°C.

JanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AM

Guajará Mirim weather by month

Every month at a glance. Click a month for its detailed page.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan30° / 23°26527.512.62.8
Feb30° / 23°2562512.42.8
Mar30° / 23°25727.212.12.8
Apr30° / 23°16522.911.83.2
May30° / 22°8115.511.54.3
Jun30° / 21°336.811.45.3
Jul31° / 20°214.111.45.2
Aug33° / 21°365.611.64.0
Sep33° / 22°8513.711.93.1
Oct33° / 23°15120.812.22.7
Nov31° / 23°20723.812.52.7
Dec31° / 23°26327.112.62.7

Chance of rain

How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.

Guajará Mirim gets about 1820 mm of precipitation a year. On a typical day the chance of rain is very wet, but that rises and falls sharply with the seasons.

The wetter season lasts 7.0 months, from around Oct 4 to May 4, peaking in February at about 91% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Jul 31.

January is the wettest month by volume, with 265 mm over about 28 wet days; July is the driest, with 21 mm.

0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecwetterdrierwettermostly drysome rainoften wetvery wetFeb 19 · 91%Jul 31 · 11%
Rain on a day (%)Rain days
Jan8928
Feb8925
Mar8727
Apr7523
May5016
Jun247
Jul134
Aug196
Sep4514
Oct6621
Nov8024
Dec8727

Monthly rainfall

Over a full year, Guajará Mirim collects about 1820 mm of rain across 220 wet days — roughly 152 mm in an average month.

It doesn’t fall evenly. January is the wettest month with 265 mm, while July is the driest at just 21 mm. The three wettest months alone bring about 43% of the year’s total.

050100150200250300JanFebMarAprMayJunJulAugSepOctNovDec2652562571658133213685151207263
Rainfall (mm)Rain days
Jan26528
Feb25625
Mar25727
Apr16523
May8116
Jun337
Jul214
Aug366
Sep8514
Oct15121
Nov20724
Dec26327

Clouds and sunshine

ClearMostly clearPartly cloudyMostly cloudyOvercast

How often the daytime sky is clear, partly cloudy or overcast.

In Guajará Mirim, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.

The clearer part of the year begins around May 15 and lasts for 4.9 months, ending around October 9. The clearest month is July, when the sky is clear, mostly clear, or partly cloudy 83% of the time on average.

The cloudier part of the year begins around October 10 and lasts for 7.1 months, ending around May 14. The cloudiest month is February, when it is overcast or mostly cloudy 95% of the time.

0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JanFebMarAprMayJunJulAugSepOctNovDecJul 21 · 84%Jan 9 · 5%clearmostly clearpartly cloudymostly cloudyovercastcloudierclearercloudier
Clearer (%)Cloudier (%)
Jan694
Feb595
Mar694
Apr1684
May3664
Jun6832
Jul8317
Aug7723
Sep5644
Oct2773
Nov1288
Dec991

Daylight, sunrise and sunset

DaylightNight

Hours of daylight through the year, with sunrise and sunset times.

The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around January 1, brings about 12 h 36 min of light; the shortest, around May 26, only 11 h 24 min — a swing of roughly 1 h 12 min.

12 AM4 AM8 AM12 PM4 PM8 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDec
Daylight (h)Sunrise (AM)Sunset (PM)
Jan12.66:146:48
Feb12.46:256:47
Mar12.16:296:33
Apr11.86:296:14
May11.56:326:03
Jun11.46:406:03
Jul11.46:446:10
Aug11.66:366:15
Sep11.96:176:14
Oct12.25:596:14
Nov12.55:516:22
Dec12.65:596:36

Sunny days

How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.

Guajará Mirim averages about 6 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 0 and 22 days.

The sunnier stretch runs 4.1 months, from around May 25 to Sep 25. The sunniest month is July, with roughly 20 sunny days (bright).

The greyest month is January, down near 0 sunny days — about 98% fewer than the July peak.

0510152025JanFebMarAprMayJunJulAugSepOctNovDecgreyersunniergreyergloomymixedbrightbrilliantJul 2722 daysJan 40 days
Sunny daysSky
Jan0Gloomy
Feb0Gloomy
Mar0Gloomy
Apr1Gloomy
May5Gloomy
Jun14Mixed
Jul21Bright
Aug19Bright
Sep10Mixed
Oct3Gloomy
Nov1Gloomy
Dec1Gloomy

Humidity comfort

DryComfortableHumidMuggyOppressiveMiserable

Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.

Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.

Guajará Mirim is humid all year round — on a typical day the air feels at least humid, and there is no real dry season to wait for.

The stickiest month is January, when it feels muggy, oppressive or miserable about 100% of the time. Even in July, the mildest month, the air is dry or comfortable only 9% of the time.

0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecJul 25 · 11%Jan 1 · 0%miserablemuggyoppressivehumidhumidcomfortablehumid
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
Jan00006634
Feb00006337
Mar00005247
Apr01144351
May024125131
Jun12620674
Jul351535410
Aug461627461
Sep13513708
Oct00047520
Nov00016038
Dec00016237

Wind

Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.

This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.

Wind in Guajará Mirim is steady company: average speeds sit near 6 km/hcalm — in every month of the year, with no meaningful windy or calm season.

0510JanFebMarAprMayJunJulAugSepOctNovDeccalmJul 25 · 7 km/hMar 22 · 5 km/h
Wind speed (km/h)Feels
Jan6calm
Feb6calm
Mar5calm
Apr5calm
May6calm
Jun6calm
Jul7calm
Aug7calm
Sep6calm
Oct6calm
Nov6calm
Dec6calm

Hazard calendar for Guajará Mirim

In seasonPeak

When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.

Guajará Mirim'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

Best time to visit Guajará Mirim

TravelBeach/poolTemperatureCloudsPrecipitation

To characterize how pleasant the weather is in Guajará Mirim throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.

Around late July, Guajará Mirim is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.

Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.

The travel score favors clear, rainless days with daytime highs between 18°C and 28°C. Based on this score, the best time of year to visit Guajará Mirim for general outdoor tourist activities is from mid May to mid August, with a peak score in the first week of July.

0246810JanFebMarAprMayJunJulAugSepOctNovDecbest timetravel scoretemperaturecloudsprecipitationJul 2 · 5.4

The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Travel score (0–10)Rating
Jan2.8poor
Feb2.8poor
Mar2.8poor
Apr3.2poor
May4.3fair
Jun5.3fair
Jul5.2fair
Aug4.0fair
Sep3.1poor
Oct2.7poor
Nov2.7poor
Dec2.7poor

The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best time of year to visit Guajará Mirim for hot-weather activities is from late May to late August, with a peak score in the third week of July.

024681012JanFebMarAprMayJunJulAugSepOctNovDecbest timebeach/pool scoretemperaturecloudsprecipitationJul 16 · 7.9

The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

What to pack for Guajará Mirim, by month

EssentialRecommendedOptional

Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.

Guajará Mirim packs about the same all year — highs hold near 33°C. Across the year the things worth having are light clothes, rain gear and sun protection.

Light clothing
Warm layer
Winter coat
Rain gear
Sun protection
Windbreaker

In September, Guajará Mirim sees daytime highs around 33°C and nights near 22°C. Pack light clothes and rain gear. Worth having: sun protection. About 14 days see rain.

UV index (midday) in Guajará Mirim by month

LowModerateHighVery highExtreme

Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.

Under clear skies, the midday UV index in Guajará Mirim peaks around January 20 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near September 13 at about 4 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highModerateExtremeJan 20UV 15Sep 13UV 4
UV index (midday)Level
Jan15Extreme
Feb15Extreme
Mar14Extreme
Apr13Extreme
May10Extreme
Jun9Very high
Jul8Very high
Aug7High
Sep4Moderate
Oct12Extreme
Nov13Extreme
Dec14Extreme

Average hourly UV index in Guajará Mirim

LowModerateHighVery highExtreme

Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.

The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.

UV falls off far faster than brightness as the sun drops, so even in January the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 7 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.

JanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AM
UV ≥ 3 (h/day)UV ≥ 6 (h/day)
Jan8.57
Feb8.56.5
Mar8.56.5
Apr7.56
May75
Jun6.54.5
Jul6.54
Aug62
Sep4.50
Oct7.55.5
Nov86
Dec8.56.5

Air quality in Guajará Mirim by month

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.

Air quality in Guajará Mirim is worst in September — around 78 µg/m³ PM2.5 (unhealthy), about 9.3× the cleanest month (May, 8 µg/m³).

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

020406080JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateUnhealthyModerateSep 1275 µg/m³May 218 µg/m³
PM2.5 (µg/m³)Level
Jan12Moderate
Feb13Moderate
Mar13Moderate
Apr10Good
May8Good
Jun9Good
Jul16Moderate
Aug63Unhealthy
Sep78Unhealthy
Oct29Moderate
Nov17Moderate
Dec12Moderate
Almanac & agriculture

Growing season

Chance of a frost-free dayFrost-free year round

Guajará Mirim is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.

0%25%50%75%100%JanFebMarAprMayJunJulAugSepOctNovDecfrost-free year round
Frost-free chance (%)Frost nights
Jan1000
Feb1000
Mar1000
Apr1000
May1000
Jun1000
Jul1000
Aug1000
Sep1000
Oct1000
Nov1000
Dec1000

Growing degree days

Degree days (base 10°C)Frost-free shaded

Growing degree days tally heat above 10°C: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Guajará Mirim banks about 6,092 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around October.

02,0004,0006,000JanFebMarAprMayJunJulAugSepOctNovDec
Growing degree days (°C·days)
Jan518
Feb466
Mar519
Apr497
May493
Jun466
Jul482
Aug523
Sep534
Oct553
Nov518
Dec525

Solar energy

Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.

Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.

Guajará Mirim receives about 4.9 kWh/m² a day of solar energy — bright — and it stays remarkably steady, holding between 4.2 and 5.6 kWh/m² all year. For solar panels, output here is a flat line, not a seasonal wave.

01234567JanFebMarAprMayJunJulAugSepOctNovDecdimmoderatebrightintenseSep 255.6 kWhMay 264.2 kWh
Solar energy (kWh/m²)Level
Jan4.8Bright
Feb4.6Bright
Mar4.6Bright
Apr4.5Bright
May4.3Bright
Jun4.4Bright
Jul4.9Bright
Aug5.4Bright
Sep5.6Bright
Oct5.5Bright
Nov5.2Bright
Dec4.9Bright

Where is Guajará Mirim?

Guajará Mirim sits at 10.8°S, 65.3°W, 131 m above sea level, in Brazil. The nearest listed city is Guayaramerín, 5.0 km away.

Alto ParaísoAriquemes

Topography around Guajará Mirim

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

Within 3 km, the terrain around Guajará Mirim has only modest variations in elevation — a maximum elevation change of 44 m around an average of 124 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 247 m; within 80 km, significant variations in elevation — a maximum elevation change of 365 m.

The land around Guajará Mirim is covered by trees (37%), artificial surfaces (24%) and water (20%) within 3 km, grassland (48%) and trees (44%) within 16 km, and trees (84%) within 80 km.

3 km
44 m
16 km
247 m
80 km
365 m
treesgrasslandartificial surfaceswaterwetland
Nearby: Guayaramerín 5.0 km · Nova Mamoré 42 km · Riberalta 82 km · Buritis 177 km · Plácido de Castro 208 km · São Francisco do Guaporé 239 km · Alto Paraíso 251 km · Ariquemes 269 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 Guajará Mirim (-10.7836°, -65.3355°, elevation 131 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).