Guanacaste Weather During the Wet Season
Half of the Year, Guanacaste Province is Sunny and Dry
Of all the provinces of Costa Rica, Guanacaste has the driest climate, but it does have a rainy season. The peak season for tourism in Guanacaste and the rest of Costa Rica is during the dry season, December to March. Winter drives the tourists south to bask in the tropical, warm, sunny climate.
During the dry season, it is a lot like the summers in Central Texas, where I grew up, with temperatures of 94 to 100 degrees F in the afternoon and very dry. Thankfully, however, Guanacaste is not quite as hot as Texas. There is a little more humidity, but it is not nearly as sultry as it is in the Limón province on the Caribbean side of the country. From January to March, time passes by predictably without any significant rainfall. Changing ocean currents have something to do with this cycle.
So what you see during summer (verano, in Spanish) in the plains and coastal hills of Guanacaste is dried grass and quite a few trees without leaves. The benefit of this season is that you can usually make plans to go on an outing without the weather interfering. The dryness induces some trees to flower during this period as well, including the roble sabanas which make striking yellow or pink blooms, and the madera negro (black wood) which is used for living fence posts. The howler monkeys like to eat these blooms, by the way.
Guanacaste During the Wet Season
Don't let the "wet season" scare you away from vacationing from June to December. Most of the time, it is like you can see in the photo above, partly cloudy with a chance of rain. It rarely rains in the mornings, typically raining late in the afternoon instead. Rarely does the rain interfere with plans to go to the beach.
The period of the most intense rain occurs in September and October. Rainfall starts to slack off in November, and by mid-December, the dry season officially starts. Christmas in this province is almost always dry, but it is still green from the leftover moisture of the wet season.
At the time of this writing (2011), October has been a very wet month. It has been raining several days straight and often through the night. Perhaps it is related to the La Niña effect. There has been significant flooding in the low-lying areas. But the tourist destinations on the coast have not been affected by the rising water levels. The weather along the coast is frequently milder than what is found inland near the mountain ranges. The area around Santa Cruz and Filadelfia are significantly affected when there is a lot of rain in Guanacaste.
Below are graphs of the data from one weather station in Guanacaste for the average monthly rainfall. The total rainfall average is 1812.4 mm, or 67.8 inches.
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The Temperature and Humidity Ranges in Guanacaste
There can be a wide range of temperatures in the province. If you are in the mountainous regions, then it can be cool enough at nights for a jacket. Have a water-proof jacket for these regions, as it can also rain frequently. The temperatures in the mountains rarely get very hot, which is why these areas are great places to grow coffee.
In the lowlands areas, including the beaches, the temperature rises to the low and mid 90's during the summer months. During the rainy months, the temperature rarely gets above the high 80's. Almost all of the time, the temperatures at night get into the comfortable 70's. And the mornings are absolutely wonderful, so it is great to get up and do things early to enjoy the fresh air. In November and December, there is an increase in nighttime temperatures into the low 80's.
The humidity during the wet months averages out around 80%, but during the dry season, it is around the mid 60's to low 70's. You can feel the humidity spike up when a rainstorm is approaching or building up in the area.
Overall, Guanacaste has a very comfortable climate. But, as it said before it rains there is the humidity, and the sun can be intense between the hours of 10 and 2 when there are no clouds. So, bring a hat and some sunscreen and enjoy the outdoors. The weather is great most of the time!
Guanacaste After the Wet Season
In December, there is a distinct transition from rain to lack of rain. This is accompanied by an increase in the velocity of the winds. Sometimes the high winds make it to the coast and whip up waves where they are normally not significant. I have been to Playa Nacoscolo on the Papagayo Peninsula several times, where there are essentially no waves. But, easterly winds blowing across Bahia Culebra did make for 2-foot waves one day. A photo taken that day is shown above.
Nearer the mountains, or volcanic range, the wind velocity is the greatest, which is why ICE, the national public utility, has placed several wind power generation sites along the west slopes of the Miravalles Volcano. As you go further away from the volcanic mountain range, you experience less wind. At the airport 15 kilometers to the west of Liberia, planes change the direction of landing and take off during this part of the season, because the winds are predominantly from the east.
Because of the lack of rain, there is an effect on vegetation. The forests in the mountains along the coast and away from the mountains defoliate to a large extent. Flowering of the trees also occurs during this time, where you can see roble savannas (oaks), madera negro and Plumeria (frangipani) trees blooming, as well as other species.
Video that Includes Sights of Guanacaste During the Wet and Dry Seasons
1.Chacón. 2004. CATIE: Del conflicto a la cogestión del agua en la microcuenca del Río Nimboyores, Guanacaste, Costa Rica. (Rainfall data) Pan American Health Organization.