Climate of Oregon

Climate zones of the Continental United States.

Oregon's climate varies greatly from the western and eastern regions of the state. An oceanic climate (also called "west coast marine climate") predominates in Western Oregon, and a much drier semi-arid climate prevails east of the Cascade Range in Eastern Oregon. Major factors determining Oregon's climate include the large semi-permanent high pressure and low pressure systems of the north Pacific Ocean, the continental air masses of North America, and the Cascade mountains. Oregon's population centers, which lie mostly in the western part of the state, are generally moist and mild, while the lightly populated high deserts of Central and Eastern Oregon are much drier.

Precipitation

Oregon experiences extensive variation in rainfall

Precipitation in the state varies widely: the deserts of eastern Oregon, such as the Alvord Desert (in the rain shadow of Steens Mountain), get as little as 8 inches (200 mm) annually, while some western coastal slopes approach 200 inches (5,100 mm) annually.

Temperature range

Snowfall in Oregon is concentrated along the Cascade Range.

Oregon has a wide range of temperature extremes throughout the state, varying from a low of −54 °F (−48 °C) to a high of 119 °F (48 °C), though these record temperatures are rarely experienced. The temperature in the Willamette Valley is mild compared to the desert regions of the state, with high temperatures at or above 90 °F (32 °C) occurring only five to fifteen times per year, and low temperatures below 30 °F (−1 °C) similarly infrequent. The hottest area of the state is the southwest; Jackson County is the warmest place in the state during summer.

The High Desert region of Oregon.

hi

Monthly Normal High and Low Temperatures (°F) For Various Oregon Cities

City	Jan		Feb		Mar		Apr		May		Jun		Jul		Aug		Sep		Oct		Nov		Dec		Annual Precipitation
	hi	lo	hi	lo	hi	lo	hi	lo	hi	lo	hi	lo	hi	lo	hi	lo	hi	lo	hi	lo	hi	lo	hi	lo
Astoria	48	37	51	38	53	39	56	41	60	45	64	50	67	53	68	53	68	50	61	44	53	40	48	37	67.1 inches (1,700 mm)
Bend	40	23	44	25	51	27	57	30	65	36	73	41	81	46	81	46	72	39	62	32	46	28	40	23	11.7 inches (300 mm)
Brookings	55	42	56	42	58	42	60	44	63	47	67	50	68	52	68	53	68	51	65	48	58	45	55	41	73.4 inches (1,860 mm)
Burns	35	14	40	19	49	25	57	29	66	36	75	41	85	46	84	44	75	35	62	26	45	21	35	15	10.5 inches (270 mm)
Eugene	46	33	51	35	56	37	61	39	67	43	73	47	82	51	82	51	77	47	65	40	52	37	46	33	50.9 inches (1,290 mm)
Medford	47	31	54	33	58	36	64	39	72	44	81	50	90	55	90	55	84	48	70	40	53	35	45	31	21.1 inches (540 mm)
Pendleton	40	27	46	31	55	35	62	40	70	46	79	52	88	58	87	57	77	50	64	41	48	34	40	28	13.9 inches (350 mm)
Portland	46	37	50	39	56	41	61	44	67	49	73	53	79	57	79	58	74	55	63	48	51	42	46	37	43.1 inches (1,090 mm)
Salem	47	34	51	35	56	37	61	39	68	44	74	48	82	52	82	52	77	48	64	41	52	38	46	34	40 inches (1,000 mm)

See also

• Climate of the United States