Guanacaste weather by month
Guanacaste is warmest in March (34°C average high) and coolest in October (29°C). For warm, mostly dry weather, go December. The sea is warm enough for easy swimming all year.
Warmest month
March
34°C
Coolest month
October
29°C
Wettest month
October
502 mm
Flight from London
11h
direct, estimated
Guanacaste temperature by month
Tap a month for the detail and warmer alternatives.
| Month | Day | Night | Sea | Rain |
|---|---|---|---|---|
| January | 32°C | 25°C | 28°C | 14 mm |
| February | 34°C | 25°C | 28°C | 6 mm |
| March | 34°C | 25°C | 29°C | 15 mm |
| April | 34°C | 26°C | 30°C | 70 mm |
| May | 31°C | 25°C | 30°C | 267 mm |
| June | 29°C | 24°C | 30°C | 379 mm |
| July | 30°C | 25°C | 30°C | 240 mm |
| August | 30°C | 24°C | 30°C | 295 mm |
| September | 29°C | 24°C | 30°C | 346 mm |
| October | 29°C | 24°C | 29°C | 502 mm |
| November | 29°C | 24°C | 28°C | 214 mm |
| December | 31°C | 24°C | 29°C | 37 mm |
When to go to Guanacaste
What is the best month to visit Guanacaste for sun?
For warm, mostly dry days, go December, going by our 10-year averages.
What is the hottest month in Guanacaste?
March averages 34°C. October is the coolest at 29°C.
When does it rain most in Guanacaste?
October, with about 502 mm of rain.
When is the sea warm enough to swim in Guanacaste?
all year, when the sea averages 21°C or more.
Planning the trip? Start with our 3-day Guanacaste itinerary, and see the best time to visit Guanacaste for crowds and events.
How we measured this
Daily averages from 2016 to 2025, from the Open-Meteo historical weather archive (ECMWF ERA5 reanalysis); sea temperatures are 2023 to 2025 averages from the Open-Meteo marine archive. Rain is the average monthly total.
Going to Guanacaste?
Save the places you find on TikTok and Instagram for Guanacaste to one map, and Dream Trip will plan the days around them.
