Rainy Season in Costa Rica: Month by Month

Quick answer: Costa Rica’s rainy season — the “green season” — runs May–Nov, and October is the wettest month on both coasts: Tamarindo averages 367 mm (14.4 in) then, against 3 mm (0.1 in) in February. The dry months are Dec–Apr. The catch is that Guanacaste’s dry season is genuinely dry — 1 rain day in February — while the Arenal side never quite stops: La Fortuna still gets 19 mm (0.7 in) in its driest month.

Pick a destination to see its weather month by month and the best time to go, or pick a month to see where the weather is at its best.

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Destination

Best = an ideal daily high for the kind of trip and rain on 10 days or fewer; the rule is under the tool.

Tokyo · a city trip

Good: Mar–May, Oct–DecNo month is ideal for a city trip by our rule, but these come close.

Warmest: Aug · 89°F
Coolest: Jan · 49°F
Wettest: Jul · 16 rain days

Averages for 2006–2025: any single year can be hotter, colder or wetter.

Weather from NASA POWER daily data, 2006–2025, for the ~50 km area around each place. Right on the coast, afternoons can be a few degrees warmer than shown.

Month	High / low (°F)	Rain days	Rain (in)	Verdict
Jan	49° / 34°	5	2.4	Off (too cold)
Feb	51° / 35°	7	3.1	Off (too cold)
Mar	57° / 40°	12	5.1	Good (cool, showery)
Apr	65° / 48°	12	6	Good (showery)
May	73° / 58°	13	6.6	Good (showery)
Jun	79° / 65°	16	8.1	Off (too wet)
Jul	86° / 73°	16	6.5	Off (too wet)
Aug	89° / 75°	15	5.4	Off (too hot)
Sep	82° / 70°	16	8.7	Off (too wet)
Oct	72° / 59°	14	8.9	Good (showery)
Nov	63° / 48°	11	4.4	Good (showery)
Dec	54° / 39°	7	3.2	Good (cool)

The tool above opens on Guanacaste (Tamarindo): change the place or the month to yours, or compare San José and La Fortuna (Arenal). Below, Costa Rica month by month — rain, rain days and how warm it is.

Costa Rica month by month

Average rainfall and the number of days with at least 1 mm of rain, 2006–2025. On this page a month counts as wet when it gets more rain than an average month in that place (more than a twelfth of its year), and dry when it gets less than half an average month. The months in between are the shoulder.

Month	Guanacaste (Tamarindo)	San José	La Fortuna (Arenal)	Guanacaste (Tamarindo): rain
January	1 days — dry	9 days — dry	7 days — dry	4 mm (0.2 in)
February	1 days — dry	6 days — dry	5 days — dry	3 mm (0.1 in)
March	1 days — dry	8 days — dry	6 days — dry	10 mm (0.4 in)
April	8 days — dry	16 days — shoulder	12 days — dry	45 mm (1.8 in)
May	22 days — wet	25 days — wet	22 days — wet	264 mm (10.4 in)
June	26 days — wet	27 days — wet	25 days — wet	287 mm (11.3 in)
July	22 days — wet	26 days — wet	23 days — wet	203 mm (8.0 in)
August	23 days — wet	27 days — wet	24 days — wet	236 mm (9.3 in)
September	28 days — wet	28 days — wet	27 days — wet	317 mm (12.5 in)
October	27 days — wet	28 days — wet	27 days — wet	367 mm (14.4 in)
November	16 days — wet	23 days — wet	20 days — wet	237 mm (9.3 in)
December	4 days — dry	15 days — dry	11 days — dry	20 mm (0.8 in)

Guanacaste (Tamarindo) is wet in May–Nov and dry in Dec–Apr. San José is wet in May–Nov, shoulder in Apr and dry in Dec–Mar. La Fortuna (Arenal) is wet in May–Nov and dry in Dec–Apr.

There is a lull inside the season that Costa Ricans call the veranillo, the little summer. Tamarindo’s July averages 203 mm (8.0 in) between 287 mm (11.3 in) in June and 317 mm (12.5 in) in September, and San José does the same thing a little more gently. It is a break in the rain, not the end of it.

The wettest and driest months

Guanacaste (Tamarindo): wettest in October (367 mm (14.4 in), 27 rain days), driest in February (3 mm (0.1 in), 1 rain day). San José: wettest in October (348 mm (13.7 in), 28 rain days), driest in February (22 mm (0.9 in), 6 rain days). La Fortuna (Arenal): wettest in October (300 mm (11.8 in), 27 rain days), driest in February (19 mm (0.7 in), 5 rain days). Over the year, Guanacaste (Tamarindo) gets 1993 mm (78.5 in).

The best months to go

Guanacaste (Tamarindo): Dec · San José: Dec–Feb · La Fortuna (Arenal): Dec–Feb. When to Go rates every month on temperature, rain days and storms — open Guanacaste (Tamarindo) in the tool above and step through the year.

Plan it

FAQ

When is the rainy season in Costa Rica?

May–Nov — the months that get more rain than an average month in Guanacaste (Tamarindo). October is the wettest, at 367 mm (14.4 in) across 27 rain days, against 3 mm (0.1 in) in February (NASA POWER, 2006–2025).

Does it rain all day in the rainy season in Costa Rica?

The measure here is a day with at least 1 mm of rain, not a day of rain. In October, Guanacaste (Tamarindo) averages 27 rain days out of 31, with an average high of 84°F / 29°C.

What is the driest month in Costa Rica?

February, at 3 mm (0.1 in) across 1 rain day. The dry months, by the rule this page uses, are Dec–Apr.

When is the best time to visit Costa Rica?

When to Go rates Dec the best months for Guanacaste (Tamarindo), on temperature, rain days and — where it applies — storms. The other places on this page have their own; open the tool above on each.

Is the green season a bad time to visit Costa Rica?

It is the cheapest and greenest time, and the rain is mostly afternoon rain. The months to think hardest about are September and October, the two heaviest: Tamarindo gets 317 mm (12.5 in) and 367 mm (14.4 in) in those two months alone, about a third of its whole year.

How these numbers are made

Daily rainfall and temperature from NASA POWER (MERRA-2), averaged over 2006–2025; a rain day is a day with at least 1 mm. POWER works on a grid of about 50 km, so each place here is its neighbourhood rather than its own rain gauge: a coast, a small island or a valley under a mountain can differ from the square it sits in. The months are the part that holds; treat a single millimetre figure as an average, not a forecast.