Portland, Oregon, is widely known for its rainy climate. While this perception holds some truth, understanding the specifics of its rainfall reveals a more nuanced picture than constant downpours. This article aims to clarify the amount of rain Portland receives annually, its seasonal distribution, and the typical nature of its precipitation.
Annual Rainfall and Rainy Days
Portland receives an average annual rainfall of about 42.8 inches, comparable to the U.S. average of 38 inches. Despite its reputation, Portland does not rank among the top ten or even top fifteen wettest cities in the United States by total rainfall volume. Cities such as New Orleans, Miami, and Houston, for instance, often record significantly higher annual totals.
Portland experiences a notable number of “rainy days” each year. The city averages between 153 and 166 days with measurable precipitation annually. A rainy day is defined as one receiving at least 0.01 inches of precipitation. This high frequency of precipitation days contributes significantly to the city’s damp image, even though the total accumulation might not be as extreme as often perceived.
Monthly Rainfall Patterns
Portland’s rainfall is not evenly distributed, exhibiting distinct seasonal patterns. The wettest months occur during the late autumn and winter, with November and December seeing the highest precipitation. November averages between 5.5 and 8.8 inches of rain, while December receives around 6.8 to 6.9 inches. These months are characterized by frequent and prolonged periods of precipitation.
Conversely, the summer months are drier. July is the driest month, averaging 0.5 to 0.6 inches of rain. August sees about 0.7 inches. This leads to warm, dry summers, which are a stark contrast to the wet conditions experienced during the rest of the year. The transition months of spring and fall show gradually increasing or decreasing rainfall, respectively, bridging the gap between the wet and dry seasons.
Understanding Portland’s Rain
Portland’s reputation for rain stems less from the sheer volume of rainfall and more from its characteristic type. Rather than intense downpours, the city frequently experiences light, persistent drizzle. This misty rain lasts for extended periods, contributing to prolonged overcast skies and dampness, particularly from November through April. It is common for the rain to be a mere sprinkling or a brief drizzle, which can still lead to a “rainy day” count even with minimal accumulation.
This pattern contrasts sharply with cities that receive higher annual rainfall but through fewer, more intense storms. For example, some East Coast and Southern U.S. cities, while accumulating more total inches, experience their rain in heavy, short bursts. In Portland, the frequent, light precipitation nourishes the region’s lush greenery and influences the local outdoor culture, where many activities continue despite the persistent, gentle rain. The consistent presence of clouds and light rain shapes the city’s atmospheric feel.