hood river county climate
Introduction

Hood River County lies in the north central part of Oregon along the Columbia River. It is wholly within Climate Division 6 (North Central Oregon) established by the National Climatic Data Center. Below is a description of the climate of Division 6 followed by specific descriptions of Hood River County. Climate tables for various parameters, as observed at long-term climate stations in Hood River County, are included below.

Climate Division 6 — North Central Oregon

North Central Oregon, climatic Zone 6, is a relatively dry region lying east of the Cascade Mountains. The Cascades serve as an effective moisture barrier, causing storms to dump much of their moisture west of the peaks and leaving areas to the east in a "rain shadow." As a result, Zone 6 is generally rather dry. The region extends from the Columbia River southward over hill country to the forested mountain areas, which border climate Zone 7. The Columbia is used in irrigation, transportation and hydroelectric power, and therefore dominates the area.

This region is Oregon's major wheat producing area. Grain production on dry land farms is the main source of agricultural income except for the Hood River Valley, which produces mostly tree fruits. Despite relatively small dimensions, the latter is one of the most important production areas in the Northwest. Its annual income of approximately $60 million derives mostly from pears, apples, and cherries. Other important commodities produced in Zone 6 include green peas, irrigated truck crops, beef cattle, sheep, alfalfa, and poultry.

Just as most of Oregon, this region has a definite winter rainfall climate. The months of November through February generally receive the most precipitation due to winter storms, which bring rain to lower elevations and snow to higher ridges and peaks. Annual totals vary greatly and are proportional to elevation; some of the lower elevations receive less than 12 inches per year, while a few of the higher areas receive more than 40 inches. Occasional summer thunderstorms bring localized, occasionally heavy showers.

Figure 1 shows NOAA climate stations in Zone 6, which were in operation during the 1961-1990 period. Figure 2 shows the Hood River County region from the Oregon annual precipitation map. Table 1 lists normal monthly and annual precipitation for stations in Zone 6. Locations at the lowest elevations (adjacent to the Columbia) such as Arlington and Hermiston receive less than 10 inches per year. Precipitation increases steadily with elevation. Highest annual totals are found in the Blue Mountains along the extreme east border of the region, where totals exceeding 50 inches occur. Table 2 lists the average number of days with precipitation amounts exceeding certain thresholds.

The Columbia Gorge is a major east-west passageway connecting Zone 6 with the Willamette Valley and Oregon coast. Vigorous winds are common in and around the Gorge. During summer, wind direction is predominantly from the west, causing strong, steady winds within the Gorge and along the northern edge of Zone 6. These winds, in fact, make Hood River a world-renowned wind surfing location. Winter winds can blow from the west or the east and can reach speeds sufficient to cause widespread damage.

A major effect of the Gorge is a moderation of air temperatures near the Columbia by allowing maritime air to reach the area from the west; this can occur both in summer and winter. Occasionally, however, large-scale easterly flow brings very cold continental air to the region, resulting in extremely cold conditions. During such periods, the cold air passes westward through the Gorge, creating extreme conditions in the western valleys as well.

Table 3 lists normal monthly and annual temperatures in the region. Highest summer temperatures are observed at the low-lying points near the Columbia (i.e. Arlington, Hermiston, and Milton Freewater), while mean temperatures decrease with increasing elevation. Winter temperatures follow the same pattern with mildest temperatures at the lower elevation sites.

Table 4 lists average monthly and annual snowfall total for the various stations.

Median frost dates and length of the growing season are listed in Tables 5 and 6, respectively. These also follow the same elevation relationship evident in the temperature data: the longest growing seasons are in the mild and low elevation sites, while increasing elevation generally causes a shortening of the season. Arlington and Condon, both at nearly 3,000 feet above sea level, have much shorter growing seasons than lower sites such as The Dalles and Arlington.

Table 7 and 8 list average monthly and annual heating and growing degree days.

County Description

Established: June 23, 1908
Population: 20,600
Area: 533 sq. mi.
Economy: Argiculture, food processing, forest products and recreation.
County Seat: Hood River

The first white settlers in Hood River County filed a donation land claim in 1854. The first school was built in 1863 and a road from The Dalles was completed in 1867. By 1880 there were 17 families living in the valley. Hood River County was created in 1908 from Wasco County. Agriculture, timber, lumber and recreation are the major sources of revenue and industry. Fruit grown in the fertile valley is of such exceptional quality the county leads the world in Anjou pear production. There are more than 14,000 acres of commercial orchards growing pears, apples, cherries and peaches. Hood River County also has two ports and two boat basins, with one serving local barge traffic, a steel boat manufacturing firm and Mid-Columbia yachting interests. Windsurfing on the Columbia River is a popular sport and attracts windsurfers from all over the world.

(County information obtained from Oregon Blue Book)

Climate Tables (Hood River County, Oregon)


Table 1. Precipitation, Monthly and Annual Averages (1971-2000) (back to top)
Name
Number
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Hood River Exp Stn
4003
5.39
4.36
2.88
1.81
1.08
0.79
0.31
0.49
1.15
2.21
5.35
5.93
31.75

Table 2. Average number of Days with Selected Precipitation Amounts, Hood River Exp. Stn, 1971-2000 (back to top)
Threshold
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
.01"or more
17.7
15.7
15.3
12.7
9.0
6.3
2.8
3.5
5.7
10.1
19.4
17.8
137.0
.10"or more
10.9
9.4
8.4
5.8
3.6
2.3
0.9
1.4
2.6
5.4
12.1
10.8
74.2
.50"or more
3.8
2.7
1.4
0.7
0.2
0.3
0.1
0.2
0.7
1.1
3.5
3.9
18.7
1.00"or more
1.1
1.0
0.2
0
0
0.1
0
0
0.1
0.3
0.9
1.4
5.2

Table 3. Monthly and Annual Average Temperatures (deg F), Hood River Exp. Stn (1862), 1971-2000 (back to top)
Parameter
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Mean max
40.8
46.2
54.4
61.2
68.7
74.6
81.6
82.3
76.1
64.5
49.3
41.2
61.7
Mean min
27.9
30
34
38.4
44.3
49.7
53.3
52.1
44.3
36.7
33.3
29
39.4
Mean temp
34.4
38.1
44.2
49.8
56.5
62.2
67.5
67.2
60.2
50.6
41.3
35.1
50.6
Extreme max
63
66
78
88
102
105
104
108
100
88
69
66
108
Extreme min
-6
-9
13
25
29
32
37
36
26
19
-5
-10
-10
Mean number of days
Max 90 or more
0
0
0
0
0.6
1.9
6
6.3
1.8
0
0
0
17
Min 32 or less
20.3
15.7
11.2
4.3
0.6
0
0
0
0.8
6.7
11.5
19.5
90.1
Max 32 or less
4.9
1.6
0.1
0
0
0
0
0
0
0
0.8
3.9
11.4
Min 0 or less
0.4
0.4
0
0
0
0
0
0
0
0
0
0.3
1.2

Table 4. Snowfall, Monthly and Annual Averages (1971-2000) (back to top)
Name
Number
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Hood River Exp Stn
4003
12.4
7.2
0.9
0
0
0
0
0
0
0.1
3.9
7.9
33.0

Table 5. Median Spring and Fall Frost Dates, Hood River Exp. Stn, 1971-2000 (back to top)
Percentile
Last Date in Spring of Low Temperatures (deg F)
First Date in Fall of Low Temperatures (deg F)
24
28
32
36
24
28
32
36
10
27-Jan
6-Mar
7-Apr
6-May
29-Oct
29-Sep
23-Sep
12-Sep
20
4-Feb
15-Mar
11-Apr
10-May
10-Nov
11-Oct
26-Sep
16-Sep
50
15-Feb
25-Mar
25-Apr
22-May
3-Dec
21-Oct
11-Oct
22-Sep
80
6-Mar
8-Apr
10-May
30-May
19-Dec
2-Nov
16-Oct
3-Oct
90
26-Mar
13-Apr
12-May
1-Jun
31-Dec
5-Nov
27-Oct
5-Oct

Table 6. Average Growing Season, Hood River Exp. Stn, 1971-2000 (back to top)
Percentile
Length of Time (Days) Between Occurrence of Temperatures ( deg F)
24
28
32
36
10
233
187
140
109
20
242
192
145
112
50
285
205
164
127
80
319
229
192
137
90
688
239
199
152

Table 7. Monthly and Annual Average Heating Degree Days (base 65°F), 1971-2000 (back to top)
Name
Number
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Hood River Exp Stn
4003
938
750
640
459
285
139
48
47
165
438
699
913
5512

Table 8. Monthly and Annual Average Growing Degree Days (base 50°F), 1971-2000 (back to top)
Name
Number
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
Hood River Exp Stn
4003
0
1
11
71
210
356
536
533
314
87
7
1
2127