Oregon's climate varies widely between the eastern and western regions of the state. In western Oregon, temperatures are generally mild due to the Pacific Ocean's moderating effect. The Pacific Ocean also provides abundant moisture, leading to regular precipitation west of the Cascade Mountains and at high elevations in the east from October to May. Temperatures in the central and eastern portions of the state exhibit a greater year-to-year and day-to-day range, and since the Cascades block the flow of moisture, it is much drier in the eastern part of the state. Typical summer high temperatures range from less than 70°F at high elevations in the Cascades to around 90°F along the eastern border (1991–2020 averages). Average winter low temperatures generally range from the mid-30s (°F) along the coast to mid-20s in inland areas, with colder values occurring at high elevations and in desert regions. Precipitation amounts vary widely across the state, with areas west of the Cascades also experiencing a large variation in rainfall amounts across the seasons. Portions of the Oregon Coast Range receive more than 120 inches of precipitation annually, while some of the desert areas in the eastern part of the state receive less than 10 inches. Annual snowfall totals range from less than 3 inches along the coast (with many years having no measurable snow) to more than 300 inches at the highest elevations.
Time series of observed and projected temperature change (in degrees Fahrenheit) for Oregon from 1900 to 2100 as described in the caption.
Y-axis values range from negative 4 to positive 18 degrees. Observed annual temperatures from 1900 to 2024 show variability and range from negative 2.5 to positive 4.2 degrees. By the end of the century, projected increases in temperature range from 1.5 to 7.2 degrees under the lower emissions pathway, from 3.8 to 9.8 degrees under the intermediate pathway, and from 7.5 to 15.9 degrees under the higher pathway.
Annual average temperatures in Oregon have increased almost 3°F since the beginning of the 20th century (Figure 1), and 2015–2024 was the warmest decade on record. The number of extremely hot days has mostly been above average since the late 1980s, with the highest 5-year average recorded for the 2020–2024 period (Figure 2a). The state rarely experiences hot nights due to the moderating effects of the Pacific Ocean in the west and low humidity east of the Cascades; however, the number of warm nights has increased in recent years (Figure 2b). In addition to the overall trend of higher average temperatures, the state has mostly experienced below-average numbers of freezing days and very cold nights since the late 1990s (Figures 3a and 3b). In late June 2021, a high-pressure ridge over the Pacific Northwest led to an unprecedented heat wave that produced record-high temperatures at many stations and led to at least 116 deaths in Oregon, primarily in Portland. Two stations in the state recorded a high of 119°F on June 29, tying a record set in 1898.
Graph of the observed annual number of (a) extremely hot days and (b) warm nights for Oregon from 1900 to 2024 as described in the caption.
Panel A: Extremely Hot Days
Y-axis values range from 0 to 10 days. Annual values show year-to-year variability and range from 0 to 8.1 days. Five-year values also show variability and are mostly near or below the long-term average of 2.2 days between 1900 and 1984 but are all above average since 1985 except for the 2010 to 2014 period. The 1950 to 1954 period has the lowest 5-year value at 0.5 days, and the 2020 to 2024 period has the highest at 6.1 days.
Panel B: Warm Nights
Y-axis values range from 0 to 25 nights. Annual values show year-to-year variability and range from 0.3 to 21 nights. Five-year values also show variability and are mostly near or below the long-term average of 4.3 nights between 1900 and 1989 but are all above average since 1990. The 1950 to 1954 period has the lowest 5-year value at 1.1 nights, and the 2020 to 2024 period has the highest at 13.8 nights.
Graph of the observed annual number of (a) freezing days and (b) very cold nights for Oregon from 1900 to 2024 as described in the caption.
Panel A: Freezing Days
Y-axis values range from 0 to 28 days. Annual values show year-to-year variability and range from 0.6 to 23.9 days. Five-year values also show variability and are below the long-term average of 7.3 days for the 1900 to 1904 period, mostly near or above average between 1905 and 1994, and all near or below average since 1995 except for the 2015 to 2019 period The 1900 to 1904 and 1995 to 1999 periods have the lowest 5-year value at 4.2 and 4.5 days, respectively, and the 1985 to 1989 period has the highest at 10.3 days.
Panel B: Very Cold Nights
Y-axis values range from 0 to 8 nights. Annual values show year-to-year variability and range from 0 to 7.6 nights. Five-year values also show variability and are below the long-term average of 1.7 nights for the 1900 to 1904 period, all near or above average between 1905 and 1949 except for the 1940 to 1945 period, all near or below average between 1950 and 1969 except for the 1955 to 1959 period, and all above average between 1970 and 1994 except for the 1980 to 1984 period. Since 1995, all 5-year values are below average. The 2000 to 2004 and 2020 to 2024 periods have the lowest 5-year values at 0.4 nights and 0.5 nights respectively, and the 1915 to 1919 and 1930 to 1934 periods have the highest at 3.3 and 3.1 nights, respectively.
Precipitation varies widely throughout the year and from year to year. Statewide total annual precipitation has ranged from a low of 22.2 inches in 1930 to a high of 48.9 inches in 1996 and shows no overall trend; however, values have mostly been below average since the early 2000s (Figure 4). Unlike many areas of the United States, Oregon has not experienced an upward trend in the frequency of extreme precipitation events (Figure 5). The number of 2-inch extreme precipitation events has been highly variable with no clear long-term trend.
Graph of the observed total annual precipitation for Oregon from 1895 to 2024 as described in the caption.
Y-axis values range from 20 to 52 inches. Annual values show year-to-year variability and range from 22.2 to 48.9 inches. Five-year values also show variability and are all above the long-term average of 32.0 inches between 1895 and 1909, all below average between 1910 and 1939, and all near or above average between 1940 and 1984 except for the 1965 to 1969 and 1975 to 1979 periods. Since 1985, 5-year values are all below average except for the 1995 to 1999 period. The 1930 to 1934, 1985 to 1989, and 2000 to 2004 periods have the lowest 5-year values at 28.4, 28.1, and 28.5 inches, respectively, and the 1980 to 1984 and 1995 to 1999 periods have the highest at 38.4 and 39.5 inches, respectively.
Graph of the observed annual number of 2-inch extreme precipitation events for Oregon from 1900 to 2024 as described in the caption.
Y-axis values range from 0.0 to 3.0 events. Annual values show year-to-year variability and range from 0 to 2.8 days. Five-year values also show variability and are above the long-term average of 0.7 events for the 1900 to 1904 period, all below average between 1905 and 1934 except for the 1920 to 1924 period, and all near or above average between 1935 and 1984 except for the 1950 to 1954 and 1975 to 1979 period. Since 1985, all 5-year values are near or below average except for the 1995 to 1999 period, which has the highest 5-year value at 1.3 events. The 1985 to 1989 and 2000 to 2004 periods have the lowest 5-year values at 0.3 and 0.4 events, respectively.
Oregon seldom experiences severe thunderstorms that produce damaging hail or tornadoes; however, the state does face threats from extreme precipitation. These events are often associated with atmospheric rivers—a phenomenon in which a narrow band of very moist air is transported from tropical latitudes of the Pacific Ocean to the West Coast. An atmospheric river that struck Oregon in early February 1996 brought extremely heavy rain to northwest Oregon, with Laurel Mountain receiving more than 23 inches over 3 days and Eugene recording 5.2 inches in 24 hours. Rain at high elevations led to rapid snowmelt, causing landslides and flooding that killed at least eight people in the state. More recently, in October 2021 an extreme low-pressure system in the eastern Pacific generated hurricane-force winds and waves up to 45 feet off the coast, capsizing a 42-foot sailboat and killing two on board. In early December 2023, atmospheric rivers dropped 10–20 inches of rain at high elevations, causing rapid snowmelt and flooding that led to two deaths. In November 2024, a bomb cyclone—a storm system that rapidly intensifies—off the Pacific Coast brought 2 to 3 feet of snow and winds of 70 mph, causing lengthy power outages.
Long-term periods of wet and dry spells can have critical impacts on water supplies. Drought is a frequent concern in Oregon, where water supplies are reliant on snowpack, precipitation, and groundwater. Virtually the entire state was in drought in 2001, 2015, 2021, and 2022, with impacts on agriculture, municipal water systems, hydropower, recreation, fisheries, and wildfire. While a few areas in eastern Oregon experience a primary or secondary peak in precipitation in May, most parts of the state receive the bulk of their annual precipitation during the winter months; thus, snowpack at higher elevations is an important source of water during the drier summer months (Figure 6). Rising temperatures are expected to raise the snow line (the average lowest elevation at which snow falls) and increase the likelihood that precipitation falls as rain instead of snow. This would reduce water storage in the snowpack, particularly at those lower mountain elevations that are now on the margins of reliable snowpack accumulation. Higher spring temperatures are also expected to result in earlier melting of the snowpack, further decreasing water availability for critical sectors such as agriculture and recreation. Such reductions in water availability would also be of particular concern for areas that depend on hydroelectric power or on snowmelt for irrigation. For example, the 2015 snow drought and subsequent water supply shortage caused hundreds of millions of dollars in crop losses, as well as severely impacting local fish populations due to record-low river and stream levels and warmer-than-average water temperatures.
Time series of the annual variations in the April 1 snow water equivalent at Tangent, Oregon, from 1952 to 2024.
Y-axis values range from 0 to 45 inches. Annual values show year-to-year variability and range from 0 inches in 1992 and 2015 to 41.6 inches in 1974. Between the early 1950s and mid-1970s, annual values are mostly between 15 and 30 inches; between the late 1970s and early 2010s, they are mostly between 5 and 25 inches; and since the late 2010s, they are mostly between 5 and 20 inches.
Drought increases the risk of wildfires, which have become more severe and more costly in recent years. The Long Draw fire in 2012 was the state's largest since the 1860s, burning more than half a million acres in southeastern Oregon. The combined Labor Day fires of 2020 were even larger, resulting in historic levels of wildfire damage, with more than 2,000 structures burned. More than 1.1 million acres burned across the state in 2020, and in 2024 that figure was even higher, at 1.8 million acres. Naturally occurring droughts are expected to be more intense because higher temperatures will increase evaporation rates and soil moisture loss during dry spells. The earlier melting of mountain snowpack may also lead to a reduction in soil moisture during the summer months. As a result, the frequency and severity of wildfires are projected to increase.
Under the intermediate and higher emissions pathways, historically unprecedented warming is projected during this century (Figure 1). Even under the lower emissions pathway, some projections show annual average temperatures exceeding historical record levels by the middle of the century. However, projections for all three pathways show a large range of potential temperature increases, and some projections for the lower pathway are comparable to recent observed values. Increases in heat wave intensity are projected, but the intensity of cold waves is projected to decrease.
Under the intermediate emissions pathway, projected increases in total annual precipitation by midcentury are statistically significant in parts of northern and eastern Oregon but are less certain elsewhere (Figure 7). There is also uncertainty in projections for seasonal precipitation. Extreme precipitation events are projected to become more frequent. The combination of more extreme precipitation events and more winter and spring precipitation falling as rain rather than snow is expected to increase the risk of flooding.
Map of the contiguous United States showing the projected changes in total annual precipitation by the middle of this century as described in the caption. The state of Oregon is outlined in black.
Legend values range from less than negative 10 to greater than positive 15 percent. Note: unless otherwise specified, projected values are not statistically significant.
Oregon
Western Oregon is projected to see increases in total annual precipitation of up to 5 percent, while central and eastern Oregon are expected to see increases of 5 to 10 percent, with statistically significant increases in the 5 to 10 percent range in northern and eastern parts of the state.
Contiguous US
Projected increases in total annual precipitation are as follows: up to 5 percent for most of the Southeast, as well as the central Midwest, central Great Plains, central West, and Northwest; and 5 to 10 percent for all of the Northeast, as well as portions of the Mid-Atlantic, Southeast, northern Midwest, northern Great Plains, and Pacific Northwest, with statistically significant increases in the 5 to 10 percent range for the Northeast, northeastern Midwest, and portions of the northern Great Plains and Pacific Northwest.
Projected decreases of up to 5 percent are expected across most of Texas, New Mexico, and Arizona, as well as southern California.
Sea level rise is a concern in all coastal areas, but the situation in Oregon is complex. On average, the state experienced about 2 inches of sea level rise between 1970 and 2020—compared to 6 inches for the contiguous US as a whole—and projections under the Intermediate sea level scenario show additional increases of about 5 inches by 2050 and 11 inches by 2070 (Figure 8). Across the five scenarios shown in Figure 8, the projected increases from 2020 to 2070 range from about 0.5 to 3 feet. However, due to geological processes, parts of the Oregon coast are rising, a phenomenon known as uplift, while others are subsiding (sinking). Rising land offsets sea level rise—offering some protection—while sinking land increases it. In coming decades, however, the rate of sea level rise is projected to exceed the rate of uplift along the entire Oregon coast, resulting in an overall increase in sea level for all locations. Sea level rise is also associated with high-tide flooding, which occurs when one or more factors—sea level rise, winds, changes in ocean currents, full or new moons—push water levels above the normal high-tide mark. These events, which can damage infrastructure, cause road closures, and overwhelm storm drains, are expected to occur more frequently in Oregon as sea levels continue to rise.
Two time series of observed and projected relative sea level change for (a) the contiguous US and (b) Oregon from 1970 to 2070 as described in the caption.
Y-axis values range from negative 1 to positive 4 feet for both graphs. Legends in both graphs denote sources of historical data and scenarios for projections. Line colors for historical data are black for tide gauge data and orange for satellite data. Line and shading colors for projections based on five scenarios are as follows: light blue, Low; medium blue, Intermediate-Low; dark blue, Intermediate; yellow, Intermediate-High; and dark orange, High.
Panel A: Contiguous US
Tide gauge and satellite data generally show increases but with year-to-year variability. Projected data show increases under all scenarios. Tide gauge values range from a minimum of negative 0.3 feet in 1976 to a maximum of positive 0.4 feet in 2023. Satellite values range from a minimum of 0.0 feet in 1994 to a maximum of 0.4 feet in 2023. Projected sea level median values (lines) for the Low scenario range from 0.3 feet in 2020 to 1.1 feet in 2070, compared to 0.4 feet in 2020 to 3.1 feet in 2070 for the High scenario. Likely ranges (shading) become wider over the period shown. The range of likely values in 2070 for each of the five scenarios are as follows: Low scenario, from 0.9 to 1.4 feet; Intermediate-Low, 1.2 to 1.7 feet; Intermediate, 1.5 to 2.2 feet; Intermediate-High, 1.8 to 3.1 feet; and High, 2.4 to 3.8 feet.
Panel B: Oregon
All historical and future scenario lines show increases lower than those in the contiguous US graph. Tide gauge values range from a minimum of negative 0.3 feet in 1985 to a maximum of positive 0.3 feet in 1983. Satellite values range from a minimum of negative 0.1 feet in 1999 to a maximum of positive 0.2 feet in 2015. Projected sea level median values (lines) for the Low scenario range from 0.1 feet in 2020 to 0.4 feet in 2070, compared to 0.2 feet in 2020 to 2.5 feet in 2070 for the High scenario. Likely ranges (shading) become wider over the period shown. The range of likely values in 2070 for each of the five scenarios are as follows: Low scenario, from 0.3 to 0.6 feet; Intermediate-Low, 0.6 to 0.9 feet; Intermediate, 0.8 to 1.5 feet; Intermediate-High, 1.2 to 2.4 feet; and High, 1.8 to 3.1 feet.
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