Climate and average weather in Aserrí

In Aserrí, the weather is warm, wet, and partly cloudy and remarkably steady, with daytime highs holding near warm levels all year. The wettest stretch peaks around October.

Best: early January to late March

Over the course of the year, the temperature in Aserrí typically varies from 14°C to 23°C, and is rarely below 12°C or above 25°C. March is the hottest month of the year, while November is the coldest.

Based on the travel score, the best time of year to visit Aserrí for warm-weather activities is from early January to late March.

Hottest
Mar
23°
Coldest
Nov
15°
Wettest
Oct
537 mm
Driest
Feb
27 mm
Rain / yr
3338 mm
254 wet days
Daylight
11.4–12.6 h
shortest–longest
Elevation
1,338 m
9.9°N
Clearest
Feb
44% cloud

Aserrí 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 early January to late March.

Temperature through the year

Average highAverage lowShaded bands: 10–90% of days

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

Temperatures in Aserrí stay fairly even through the year, without a distinct hot or cool season. The warmest month is March, with an average high of 23°C and low of 14°C; the coolest is November, with an average low of 15°C and high of 21°C.

Days typically run about 7°C warmer than nights year-round.

10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDec
Avg high (°C)Avg low (°C)
Jan2214
Feb2314
Mar2314
Apr2315
May2216
Jun2216
Jul2215
Aug2215
Sep2215
Oct2215
Nov2115
Dec2214

Average hourly temperature in Aserrí

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 March afternoons, near 23°C, and coldest before dawn in November, near 15°C.

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

Aserrí 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
Jan22° / 14°295.911.57.4
Feb23° / 14°275.611.77.7
Mar23° / 14°409.911.97.0
Apr23° / 15°12319.712.25.1
May22° / 16°45528.812.43.6
Jun22° / 16°45828.912.63.4
Jul22° / 15°34028.112.53.6
Aug22° / 15°43129.312.33.5
Sep22° / 15°50929.912.13.3
Oct22° / 15°53730.211.83.3
Nov21° / 15°29924.911.54.1
Dec22° / 14°8813.111.46.1

Chance of rain

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

Aserrí gets about 3338 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 7.3 months, from around Apr 18 to Nov 26, peaking in September at about 100% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Jan 29.

October is the wettest month by volume, with 537 mm over about 30 wet days; February is the driest, with 27 mm.

0%10%20%30%40%50%60%70%80%90%100%110%JanFebMarAprMayJunJulAugSepOctNovDecdrierwetterdriermostly drysome rainoften wetvery wetSep 16 · 100%Jan 29 · 14%
Rain on a day (%)Rain days
Jan216
Feb196
Mar3310
Apr6620
May9229
Jun9629
Jul9128
Aug9429
Sep10030
Oct9730
Nov8225
Dec4313

Monthly rainfall

Over a full year, Aserrí collects about 3338 mm of rain across 254 wet days — roughly 278 mm in an average month.

It doesn’t fall evenly. October is the wettest month with 537 mm, while February is the driest at just 27 mm. The three wettest months alone bring about 45% of the year’s total.

050100150200250300350400450500550600JanFebMarAprMayJunJulAugSepOctNovDec29274012345545834043150953729988
Rainfall (mm)Rain days
Jan296
Feb276
Mar4010
Apr12320
May45529
Jun45829
Jul34028
Aug43129
Sep50930
Oct53730
Nov29925
Dec8813

Clouds and sunshine

ClearMostly clearPartly cloudyMostly cloudyOvercast

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

In Aserrí, 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 November 27 and lasts for 4.7 months, ending around April 19. The clearest month is February, when the sky is clear, mostly clear, or partly cloudy 74% of the time on average.

The cloudier part of the year begins around April 20 and lasts for 7.3 months, ending around November 26. The cloudiest month is September, when it is overcast or mostly cloudy 99% 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%JanFebMarAprMayJunJulAugSepOctNovDecFeb 1 · 78%Sep 14 · 1%clearmostly clearpartly cloudymostly cloudyovercastclearercloudierclearer
Clearer (%)Cloudier (%)
Jan7228
Feb7426
Mar6238
Apr3169
May496
Jun298
Jul397
Aug298
Sep199
Oct298
Nov1585
Dec5149

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 June 6, brings about 12 h 36 min of light; the shortest, around January 1, 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)
Jan11.56:015:30
Feb11.76:015:41
Mar11.95:485:44
Apr12.25:305:43
May12.45:195:46
Jun12.65:195:54
Jul12.55:265:58
Aug12.35:315:50
Sep12.15:295:32
Oct11.85:285:15
Nov11.55:355:08
Dec11.45:505:15

Sunny days

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

Aserrí averages about 4 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 0 and 15 days.

The sunnier stretch runs 4.4 months, from around Dec 1 to Apr 12. The sunniest month is February, with roughly 15 sunny days (mixed).

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

05101520JanFebMarAprMayJunJulAugSepOctNovDecsunniergreyersunniergloomymixedbrightFeb 415 daysMay 290 days
Sunny daysSky
Jan14Mixed
Feb13Mixed
Mar11Mixed
Apr4Gloomy
May0Gloomy
Jun0Gloomy
Jul0Gloomy
Aug0Gloomy
Sep0Gloomy
Oct0Gloomy
Nov1Gloomy
Dec8Mixed

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.

In Aserrí, how humid it feels changes dramatically over the year.

The more humid part of the year lasts 6.6 months, from around May 2 to November 18. The muggiest month is June, when the air feels humid, muggy or worse about 91% of the time.

The most comfortable stretch runs from around November 19 to May 1, and January is the most comfortable month — the air is dry or comfortable 98% of the time.

0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecJan 16 · 99%Jun 10 · 6%humidcomfortabledrycomfortablehumidcomfortable
Dry (%)Comfortable (%)Humid (%)Muggy (%)
Jan455320
Feb534430
Mar435250
Apr1759230
May124741
Jun09910
Jul025750
Aug023770
Sep017830
Oct021790
Nov148510
Dec1668160

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.

Across the year, average wind speed in Aserrí is typically calm, near 5 km/h, and varies little with the seasons.

The windier part of the year lasts 4.4 months, from around Nov 18 to Mar 31. The windiest month is January, averaging about 6 km/h (calm).

The calmer part of the year runs from around Apr 1 to Nov 17, with September the calmest month at about 3 km/h.

0510JanFebMarAprMayJunJulAugSepOctNovDecwindiercalmerwindiercalmJan 13 · 6 km/hSep 20 · 3 km/h
Wind speed (km/h)Feels
Jan6calm
Feb6calm
Mar5calm
Apr4calm
May4calm
Jun4calm
Jul4calm
Aug4calm
Sep3calm
Oct4calm
Nov5calm
Dec6calm

Hazard calendar for Aserrí

In seasonPeak

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

Aserrí's rainy season runs May–November, 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 Aserrí

TravelBeach/poolTemperatureCloudsPrecipitation

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

Around late March, Aserrí 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 Aserrí for general outdoor tourist activities is from late December to late March, with a peak score in the last week of January.

0246810JanFebMarAprMayJunJulAugSepOctNovDecbest timetravel scoretemperaturecloudsprecipitationJan 31 · 7.9

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
Jan7.4good
Feb7.7ideal
Mar7.0good
Apr5.1fair
May3.7fair
Jun3.5poor
Jul3.6fair
Aug3.5fair
Sep3.3poor
Oct3.4poor
Nov4.1fair
Dec6.1good

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 Aserrí for hot-weather activities is from late December to early April, with a peak score in the first week of March.

024681012JanFebMarAprMayJunJulAugSepOctNovDecbest timebeach/pool scoretemperaturecloudsprecipitationMar 5 · 5.8

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 Aserrí, 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.

Aserrí packs about the same all year — highs hold near 23°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 March, Aserrí sees daytime highs around 23°C and nights near 14°C. Pack sun protection. Worth having: light clothes and rain gear. About 10 days see rain.

Sea temperature near Aserrí

Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.

The sea at the nearest coast (about 54 km away) is warmest in March at about 30°C and coldest in November near 28°C.

The water stays above 20°C all year — warm enough for a swim any month.

26°28°30°32°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan29Tropical
Feb29Tropical
Mar30Tropical
Apr30Tropical
May29Tropical
Jun29Tropical
Jul29Tropical
Aug29Tropical
Sep29Tropical
Oct28Tropical
Nov28Warm
Dec28Tropical

UV index (midday) in Aserrí 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 Aserrí peaks around March 19 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 10 (extreme).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeMar 19UV 15Dec 16UV 10
UV index (midday)Level
Jan12Extreme
Feb14Extreme
Mar15Extreme
Apr14Extreme
May13Extreme
Jun13Extreme
Jul13Extreme
Aug13Extreme
Sep13Extreme
Oct12Extreme
Nov12Extreme
Dec10Extreme

Average hourly UV index in Aserrí

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 March the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 6.5 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)
Jan7.55.5
Feb86
Mar8.56.5
Apr86.5
May8.56.5
Jun8.56.5
Jul8.56.5
Aug86.5
Sep86.5
Oct7.55.5
Nov7.55.5
Dec75

Air quality in Aserrí 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 Aserrí is worst in May — around 19 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (January, 9 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodMay 1718 µg/m³Jan 149 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb10Good
Mar11Good
Apr17Moderate
May19Moderate
Jun17Moderate
Jul18Moderate
Aug17Moderate
Sep16Moderate
Oct14Moderate
Nov12Good
Dec10Good
Almanac & agriculture

Growing season

Chance of a frost-free dayFrost-free year round

Aserrí 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. Aserrí banks about 3,081 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around May.

01,0002,0003,000JanFebMarAprMayJunJulAugSepOctNovDec
Growing degree days (°C·days)
Jan239
Feb227
Mar268
Apr270
May279
Jun266
Jul269
Aug266
Sep254
Oct257
Nov243
Dec244

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.

Aserrí receives about 4.6 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 3.7 and 6.0 kWh/m².

The brighter stretch of the year lasts 4.4 months, from around Dec 27 to May 9. The brightest month is March, averaging about 6.0 kWh/m² (intense).

The dimmest month is November, down near 3.8 kWh/m² — roughly 37% less than the March peak.

01234567JanFebMarAprMayJunJulAugSepOctNovDecbrighterdimmerdimmoderatebrightintenseMar 196.0 kWhNov 113.7 kWh
Solar energy (kWh/m²)Level
Jan5.1Bright
Feb5.7Bright
Mar6.0Intense
Apr5.7Bright
May4.4Bright
Jun4.2Bright
Jul4.2Bright
Aug4.3Bright
Sep4.2Bright
Oct3.8Moderate
Nov3.7Moderate
Dec4.4Bright

Where is Aserrí?

Aserrí sits at 9.9°N, 84.1°W, 1,338 m above sea level, in Costa Rica. The nearest listed city is San Juan de Dios, 2.0 km away.

Topography around Aserrí

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

Within 3 km, the terrain around Aserrí has large variations in elevation — a maximum elevation change of 871 m around an average of 1,428 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,984 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,764 m.

The land around Aserrí is covered by trees (67%) and artificial surfaces (22%) within 3 km, trees (63%) and artificial surfaces (22%) within 16 km, and trees (67%) within 80 km.

3 km
871 m
16 km
1,984 m
80 km
3,764 m
treesgrasslandcroplandartificial surfacesbare terrainwater
Nearby: San Juan de Dios 2.0 km · San Rafael Arriba 3.0 km · San Miguel 4.0 km · San Felipe 5.0 km · Patarrá 7.0 km · San Jose 8.0 km · Curridabat 9.0 km · San Pedro 9.0 km

Costa Rica travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 59% of US
price level, 2025
GDP per capita
$19,970
2025
Happiness
7.4 / 10
World Happiness, 2025
Safe drinking water
81%
of population, 2024
Homicide rate
17.7
per 100k, 2023
Road deaths
14.8
per 100k/yr, 2019
Income group
High
World Bank
English
Moderate
EF EPI 516
Religion
Roman Catholic 48%none 27%Evangelical and Pentecostal 20%other 3%

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 Aserrí (9.8614°, -84.0927°, elevation 1,338 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).