How Much Rain Falls in the US in a Year?

The amount of precipitation, including rain, that falls on the contiguous United States each year varies greatly from one region to the next. Assessing an average for the entire nation is somewhat problematic, but it is possible to determine that if all the rain that falls during an average year were to occur during a single nationwide storm, the entire country would be covered to a depth of about 30 inches (76 cm). Many factors affect what happens to rain after it reaches the ground, including the topography of the land, the presence of or lack of vegetation and the degree of urbanization in the area.

More facts about US rain patterns:

• Louisiana is considered the wettest of all the contiguous US states, with an average annual rainfall of 56 inches (142 cm). Nevada is the driest state, with an average annual rainfall of less than 10 inches (25 cm).


• Yuma, Arizona, is considered the driest city in the US, with an average annual precipitation of less than 3 inches (7.6 cm). By contrast, the city of Quillayute, Washington, is the wettest in the contiguous US, with average annual precipitation of 105.50 inches (268 cm).


• Hilo, Hawaii, is the wettest city anywhere in the US, with an average annual rainfall of 128 inches (325 cm).

Frequently Asked Questions

What is the average annual rainfall in the United States?

According to the National Oceanic and Atmospheric Administration (NOAA), the average annual rainfall for the contiguous United States is about 30 inches. However, this figure varies widely across different regions, with some areas receiving significantly more due to local climate patterns and geographic features.

Which region in the US receives the most rainfall?

The Pacific Northwest, particularly the western side of the Olympic Peninsula in Washington State, is renowned for its high precipitation levels. The Hoh Rainforest, for instance, can receive up to 170 inches of rain annually, making it one of the wettest places in the continental US.

How does rainfall in the US compare to other countries?

Rainfall in the US is quite diverse, but on average, it is less than in some tropical countries. For example, India receives an average of about 120 inches of rain per year, primarily due to the monsoon season. In contrast, the US experiences a mix of dry and wet climates, leading to a lower national average.

What are the driest areas in the US?

The driest areas in the US are found in the desert Southwest. Death Valley in California, known for being one of the hottest and driest places on Earth, averages less than 2 inches of rain per year. Similarly, parts of Nevada, Arizona, and New Mexico also experience very low annual rainfall.

How has rainfall in the US changed over time?

Climate change has altered rainfall patterns in the US, with some areas experiencing more intense and frequent rainfalls, while others are becoming drier. NOAA's climate data indicates that the Northeast and Midwest have seen significant increases in heavy precipitation events over the last few decades, whereas the Southwest has become drier.

Does the US experience extreme rainfall events?

Yes, the US is subject to extreme rainfall events, often associated with hurricanes, tropical storms, and other severe weather systems. For instance, Hurricane Harvey in 2017 set a record for the most rainfall from a single storm in the US, with peak accumulations of 60.58 inches in Nederland, Texas, as reported by the National Weather Service.