Precipitation

Oregon is known for having lots of rain. The reality is far more complicated. While some areas in the Oregon Coast Range are among the rainiest in the U.S, most of Oregon is subject to extremely dry summers. Most of Eastern Oregon is dry throughout the year.

Created by Gareth Baldrica-Franklin, Institute for Water and Watersheds, Oregon State University

Annual

The Cascade Mountains are the cause of the stark contrast between Eastern and Western Oregon. They form a "rain shadow", effectively shielding the interior parts of the state from precipitation.

Avg. Rainfall
in Inches

< 10

10 - 20

20 - 30

30 - 40

40 - 60

60 - 80

80 - 100

100 - 140

> 140

January

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

February

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

March

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

April

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

May

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

June

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

July

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

August

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

September

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

October

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

November

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30

December

Avg. Rainfall
in Inches

< 1

1 - 2

2 - 5

5 - 10

10 - 15

15 - 20

20 - 25

25 - 30

> 30