The Tropical Rhythm of San Andrés
Sitting just 12 degrees north of the equator, San Andrés enjoys a tropical monsoon climate defined by remarkable temperature stability and two distinct moisture-driven seasons. While the calendar may say winter or summer elsewhere, locals live by the pulse of the rain and the steady push of the trade winds. The island is famous for its "sea of seven colors," a visual phenomenon amplified by the high-angled equatorial sun.
Seasonal Trends
There is no true "winter" here; instead, the year is split into the dry season and the wet season.
- The Dry Season (January to April): This is the sunniest time of year. Rainfall is rare, with March typically being the driest month. Cloud cover is minimal, allowing for nearly 9 hours of daily sunshine. During these months, the air feels slightly crisper due to lower humidity levels (averaging around 77-78%).
- The Wet Season (May to December): Humidity rises and cloud cover increases. October and November are the wettest months, often seeing significant afternoon downpours. However, rain in San Andrés is rarely a day-long event; it usually arrives in intense, short-lived tropical bursts that quickly give way to steam and sun.
Daily Weather Behavior
The day in San Andrés follows a predictable tropical loop.
- Morning: Clear skies and calm waters are common. This is the period of lowest heat intensity.
- Midday to Afternoon: Temperatures peak around 86°F (30°C). In the wet season, this is when convection builds, often leading to scattered thunderstorms or "passing showers" that provide a brief, cooling respite.
- Evening: As the sun sets, temperatures dip slightly to a comfortable 77°F-79°F (25°C-26°C). The ocean serves as a thermal regulator, preventing the island from ever feeling truly cold.
The Influence of Trade Winds
A defining characteristic of the San Andrés climate is the Northeast Trade Winds. From late October through April, these steady breezes blow consistently across the island.
- Wind Effects: They act as a natural air conditioner, making the high humidity feel much more manageable.
- Sea Conditions: The winds create a "windier" side of the island (the east/northeast coast), where waves are more active, while the leeward (west) side remains remarkably calm and glass-like.
Specific Weather Phenomena
- Hurricane Proximity: San Andrés lies on the southern edge of the Atlantic hurricane belt. While direct hits are historically rare, the island frequently experiences the "tail end" of passing systems between August and November, resulting in increased wind speeds and heavy storm surges.
- The "Feels Like" Factor: Because humidity maintains a year-round average of 80%, the "real feel" is consistently 5-10 degrees higher than the actual thermometer reading. In September, a 88°F day can easily feel like 98°F.
Local Perspective and Adaptation
Locals operate on "island time," a pace often dictated by the heat of the afternoon sun. You will notice the island is most active in the early mornings and late evenings when the heat recedes. The common local saying "Every day is a beach day" reflects the reality that even in the wettest months, the sun is a constant presence. The architecture often features high ceilings and open ventilation to invite the trade winds indoors, a traditional adaptation to the oppressive midday humidity.
Historical Context
Data from the last 50 years shows a slow but steady warming trend on the island. While temperatures have always been stable, peak highs are occurring more frequently. Modern visitors may find the "dry" season occasionally interrupted by unseasonal tropical waves, a shift that locals have noted in recent decades as rainfall patterns become slightly less predictable than in the past.