Weather patterns in Costa Rica vary from region to region. While most locals will tell you that June is the beginning of the rainy season (also known within the tourism industry as the green season), some areas of the country receive far more precipitation than others, and geography plays a key role in determining climate differences.
This article discusses some of the factors that contribute to the existence of varying climate systems in the different regions of Costa Rica. More specifically, it focuses on typical seasonal weather patterns during the month of June.
General Climate Patterns
Costa Rica is a small tropical country that can be divided into at least four separate, easily identifiable climate regions. Nevertheless, because the country is located between 8 and 12 degrees north of the equator, it is not subject to the drastic seasonal weather changes that are typical of much of the Northern Hemisphere. Therefore, the local inhabitants usually refer to the only two well defined seasons as summer and winter, although these terms have very little to do with changes in temperature, as the weather remains fairly warm throughout the year. In Costa Rica, the term "summer" refers to the dry season, which typically lasts from late December through April, while "winter" is a term used to describe the rainy season, which usually occurs between middle to late May and late November.
These two seasons are quite well defined in the Pacific and Central regions of Costa Rica, however, they do not apply to the country's Caribbean Region. In addition, because it is such a mountainous nation, drastic differences in altitude along with various other geographical features contribute to the existence of many microclimates. These are areas that exhibit variations in the major climate patterns, which govern the the country's main climate regions.
The following sections describe what the weather is typically like during the month of June in Costa Rica's primary climate regions. While this article is too short to discuss the microclimates contained within these larger regions, it is important to reiterate that due to the factors mentioned above, the climate does vary slightly from place to place.
The Pacific Region
Costa Rica's Pacific region encompasses most of the country's west coast in addition to areas located further inland, both close to sea level and higher up on the western slopes of the Central Volcanic Mountain Range. June is the beginning of the rainy season in this part of the country, so the precipitation is heavier then than it is during the first few months of the year. Nevertheless, the mornings are usually quite sunny, and although intermittent showers are frequent, they generally don't occur before midafternoon.
The Carribbean Region
Costa Rica's east coast, the flatlands that lie further inland as well as the areas located in the eastern foothills of the Central Volcanic Mountain Range are all part of the country's Caribbean Region. Although this portion of the country is often divided into two areas known as the Northern and Southern Caribbean, climate patterns are similar throughout both these subregions.
The weather on this side of the country is far less predictable than it is on the west coast and because the Central Volcanic Mountain Range acts as a rain shadow, the Caribbean Region is much wetter than the rest of Costa Rica. In fact, the rains only subside briefly between March and April and from August through September. Therefore, June, like most months, is usually quite rainy in this area. Showers here tend to be heavy and sometimes continue for as much as several days at a time.
The Central Valley
Most of Costa Rica's small population is concentrated in the Central Valley. While the weather here is much cooler than it is in the Pacific lowlands due to the difference in altitude, the climate is quite similar with regard to precipitation. Like the west coast, sunny mornings with scattered showers in the afternoon are the norm during the month of June. Some parts of the region, however, are more exposed to precipitation that originates in the Caribbean Region, while others are completely sheltered by mountains. Therefore, cities like Heredia, which lies in the eastern portion of the valley, tend to be more rainy while places like Escazu, further to the south, are hotter and drier.
The Osa Peninsula
This southern landmass juts out of the west coast of Costa Rica just north of the Panamanian border. It is largely uninhabited and much of it is covered in dense tropical rain forest. Osa is directly exposed to moisture-laden winds that emanate from an area known as the Intertropical Convergence Zone, which shifts northward from the equator during the month of June, triggering the Central American rainy season. Its climate is also affected by humidity that travels across northern Panama and into southern Costa Rica from the Caribbean Sea, therefore it receives far more precipitation than the rest of the Pacific Coast. June is usually a very rainy month in the southwestern portion of Costa Rica, and showers in this region are typically far heavier and more consistent than they are further northward.