Experiencing rain for an average of 200 days each year might seem like a statistical anomaly. These regions are defined not by spectacular, drenching storms, but by a pervasive atmospheric dampness that delivers precipitation with regularity. While many locations are known for receiving vast amounts of annual rainfall, the 200-day metric is characterized by the sheer frequency of drizzle, mist, or light showers. This consistent moisture shapes the geography and daily life in these unique environments.
Understanding the High-Frequency Rainfall Metric
To accurately identify these locations, it is necessary to define what constitutes a “rainy day.” In meteorology, a day is typically classified as having measurable precipitation if it records 0.1 mm (approximately 0.004 inches) of accumulated liquid water equivalent. This low threshold allows many regions to reach the 200-day mark, as precipitation often takes the form of persistent light rain or drizzle rather than heavy downpours.
This frequency-based metric differs significantly from annual rainfall volume. For example, some tropical regions receive massive total accumulation during intense, short-lived storms over fewer than 150 days per year. Conversely, a place with 200 or more rainy days might have a lower annual rainfall total, demonstrating that the precipitation is spread out as a constant, low-intensity occurrence. Understanding this distinction is crucial to appreciating the unique climatology of these high-frequency zones.
Specific Regions with 200+ Rainy Days Annually
The regions with the highest frequency of precipitation are scattered across the globe, predominantly in coastal areas where maritime influence is strong. The city of Buenaventura in Colombia, for instance, averages 258 days of rain each year, placing it among the wettest major cities by frequency. A nearby settlement, Puerto Lopez, is reported to experience measurable precipitation on over 320 days annually, making it one of the most consistently damp places on Earth.
In North America, high-frequency rainfall defines the Pacific Northwest and coastal Alaska. The town of Forks, Washington, averages approximately 206 days of measurable precipitation. Further north, Little Port Walter in Alaska records about 233 days of precipitation annually. These regions are dominated by the influence of the vast Pacific Ocean.
Across the Atlantic, a similar climate profile exists in parts of Europe. Bergen, Norway, situated on the southwestern coast, records rain on over 230 days per year. While some parts of the UK and Iceland use a higher measurement threshold (1.0 mm), the Scottish Western Highlands are generally cited as experiencing measurable rainfall on over 250 days annually. Even the city of Hilo, Hawaii, records precipitation on 211 days of the year.
Atmospheric Factors Creating Persistent Precipitation
The primary mechanism driving this persistent, high-frequency rainfall is the constant interaction between moist air masses and physical geography. These locations are almost always under a strong maritime influence, meaning they are situated near large bodies of water that supply an unending source of moisture to the atmosphere. This moisture-laden air then encounters one of two main atmospheric triggers.
Orographic Lift
One common trigger is orographic lift, where moisture-filled air is forced upward by mountain ranges or high terrain. As the air rises, it cools rapidly, causing the water vapor to condense into clouds and precipitate over the windward side of the barrier. This process is particularly pronounced in places like Bergen, Norway, and Hilo, Hawaii, where coastal mountains act as a continual wall, wringing moisture out of the passing air.
Persistent Frontal Systems
Another element is the presence of persistent frontal systems, which in mid-latitude zones are often associated with the polar front jet stream. These low-pressure systems and slow-moving weather fronts can linger over coastal areas, leading to extended periods of unsettled weather and frequent, low-intensity precipitation events. The constant passage of these systems, often aided by warm ocean currents like the Gulf Stream, ensures that conditions for cloud formation and light rain are maintained for a majority of the year.