Portland, OR Weather Forecast and Current Conditions

Day		Sky	High / Low	Precip	Wind	Humidity
Wed Dec 4		Sunny Close Hourly	47º / 33º	1%	E 13 mph	57%
2pm		Sunny	46º	1%	E 12 mph	52%
3pm		Sunny	45º	1%	E 12 mph	54%
4pm		Sunny	44º	1%	E 13 mph	55%
5pm		Clear	41º	1%	E 9 mph	62%
6pm		Clear	40º	1%	E 8 mph	65%
7pm		Clear	39º	1%	E 8 mph	67%
8pm		Clear	38º	2%	E 8 mph	69%
9pm		Clear	37º	3%	E 7 mph	71%
10pm		Clear	36º	4%	E 6 mph	73%
11pm		Clear	36º	4%	E 6 mph	74%
Thu Dec 5		Partly Cloudy View Hourly	46º / 35º	7%	E 5 mph	68%
12am		Clear	35º	4%	E 5 mph	76%
1am		Clear	34º	4%	E 6 mph	78%
2am		Clear	34º	5%	E 5 mph	80%
3am		Mostly Clear	34º	5%	E 5 mph	77%
4am		Mostly Clear	34º	5%	E 5 mph	79%
5am		Partly Cloudy	34º	5%	E 4 mph	79%
6am		Mostly Cloudy	34º	5%	E 4 mph	80%
7am		Mostly Cloudy	34º	5%	E 5 mph	80%
8am		Partly Cloudy	34º	5%	E 5 mph	80%
9am		Mostly Cloudy	36º	3%	E 5 mph	78%
10am		Mostly Cloudy	38º	2%	ENE 4 mph	72%
11am		Mostly Cloudy	40º	1%	E 4 mph	69%
12pm		Mostly Cloudy	42º	1%	E 3 mph	65%
1pm		Mostly Cloudy	44º	8%	ENE 5 mph	60%
2pm		Mostly Cloudy	45º	2%	E 4 mph	59%
3pm		Mostly Cloudy	45º	3%	E 5 mph	61%
4pm		Mostly Cloudy	44º	4%	ESE 5 mph	63%
5pm		Partly Cloudy	43º	4%	ESE 4 mph	65%
6pm		Partly Cloudy	42º	4%	E 3 mph	68%
7pm		Partly Cloudy	41º	4%	E 4 mph	70%
8pm		Partly Cloudy	40º	4%	E 3 mph	72%
9pm		Partly Cloudy	39º	4%	ENE 4 mph	74%
10pm		Partly Cloudy	39º	5%	ENE 3 mph	74%
11pm		Partly Cloudy	38º	5%	ENE 3 mph	76%
Fri Dec 6		Cloudy View Hourly	47º / 41º	5%	ESE 5 mph	72%
12am		Partly Cloudy	37º	5%	ENE 3 mph	77%
1am		Partly Cloudy	36º	6%	ENE 3 mph	79%
2am		Mostly Clear	37º	6%	ENE 3 mph	79%
3am		Mostly Clear	36º	6%	ENE 3 mph	80%
4am		Clear	36º	6%	ENE 3 mph	81%
5am		Mostly Clear	36º	6%	E 3 mph	80%
6am		Partly Cloudy	36º	6%	E 3 mph	80%
7am		Mostly Cloudy	36º	6%	E 5 mph	81%
8am		Mostly Cloudy	36º	6%	E 5 mph	80%
9am		Mostly Cloudy	37º	5%	E 4 mph	80%
10am		Cloudy	39º	4%	E 4 mph	76%
11am		Mostly Cloudy	41º	3%	ESE 4 mph	72%
12pm		Cloudy	43º	2%	ESE 4 mph	69%
1pm		Cloudy	45º	2%	ESE 4 mph	66%
Sat Dec 7		Rain	51º / 43º	80%	SSW 7 mph	85%
Sun Dec 8		Showers	50º / 38º	56%	SSW 7 mph	83%
Mon Dec 9		Partly Cloudy	46º / 33º	9%	ENE 5 mph	86%
Tue Dec 10		Mostly Cloudy	44º / 36º	17%	E 4 mph	83%
Wed Dec 11		Mostly Cloudy	46º / 41º	24%	SSE 5 mph	81%

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General Weather Conditions in Portland, OR

The coast range provides limited shielding from the maritime influence of the Pacific Ocean. The Cascade Range provides a steep high slope for the lifting moisture-laden westerly winds, which produces heavy rainfall in the western Cascade piedmont region. They also form the barrier for the Columbia River basin region and dry continental air masses. Airflow is usually northwest in Portland in spring and summer and southeast in fall and winter, interrupted occasionally by outbreaks of dry continental air east through Cascade passes and across ridge tops. When such an outbreak occurs, extreme high or low temperatures are usually experienced in the Portland area.

Portland has a very definite winter rainfall climate. About 88 percent of the annual total occurs in October through May, nine percent in June and September, while only 3 percent comes in July and August. The average annual precipitation is 37.33 inches (948.2 mm). December is the wettest month, and July, the driest. Precipitation is mostly rain; on the average only 17 days each year have snow. Snowfall is seldom more than a couple of inches, and it generally lasts only a few days. The annual average is only seven inches (178 mm) with January having the most. Snowfall has fallen in every month from November through May. The greatest measured snowfall in 24 hours was just under 11 inches (279 mm) recorded in January 1971.

Each season is clearly marked. Winter is mild, cloudy and wet with southeast surface winds predominating. Summer is marked by mild temperature, with prevailing northwest winds and very little precipitation. Fall and spring are transitional in nature, with frequent periods of ground fog. An average of 18 days during October record foggy conditions while only three days during July can expect fog. At all times, incursions of marine-tempered air are a frequent moderating influence. Outbreaks of continental air from east of the Cascade Mountains flow through the Columbia Gorge at near sea level and spread into the Portland area associated with the movement of Pacific storms offshore on a northeast storm track. In winter this brings the coldest weather, and the extremes of low temperature are registered in the cold airmass. Freezing rain and ice glaze often are transitional effects. In summer the hot, dry, continental air brings the highest temperatures. Extreme temperatures below zero are very infrequent. The absolute lowest ever reached is 3°F below zero (-19.4°C) recorded in February 1950. Extreme temperatures above 100°F (37.8°C) have occurred during each month from May through September; the absolute highest temperature is 107°F (41.6°C) recorded in July 1942, July 1965 and August 1981. Temperatures 90°F (32.2°C) or higher are reached every year, but seldom persist for more than 2 or 3 days before the warm spell is broken by a flow of cool, moist air from the ocean. The average annual temperature for Portland is 53.9°F (12.1°C). The average maximum is 63°F (17.2°C) while the average minimum is 45°F (7.2°C).

Destructive storms are infrequent in the Portland area. Surface winds seldom exceed gale force. Thunderstorms are infrequent, occurring, on average, only seven days each year. Tornadoes with the funnel cloud reaching the ground are rare and there are rare occurrences of heavy rain even though winter rains may persist for days at a time. Ice forms occasionally, but it is seldom heavy enough to affect navigation seriously, although navigation by small craft may be difficult.