Location
The Okanagan Valley is approximately 300 kilometres from the Pacific Ocean. The valley is long and narrow and runs for 160 kilometres from the US border at 49 to 50 degrees north.
Sub-regions
The Pacific Agri-food Research Centre (PARC) has identified five sub-regions. There are significant climatic differences from north to south, for example:
Kelowna – 1200 Celsius degree days and 12 inches average annual rainfall.
Osoyoos – 1450 Celsius degree days and 8 inches average annual rainfall.
Sub-region 1
Kelowna
1200 degree days.
Heavier soils with sandy loam, clay and limestone.
Common varietals: Pinot Noir, Pinot Gris, Pinot Blanc, Riesling, Chardonnay, others.
Sub-region 2
Naramata
1319 degree days.
Long frost-free autumn due to lake proximity and sloping aspect.
Common varietals: Pinot Noir, Pinot Gris, Pinot Blanc, Chardonnay, Merlot, others.
Sub-region 3
Okanagan Falls
1407 degree days.
Diverse soils and aspects, with some vineyards on terraced slopes.
Common varietals: Riesling, Gewurztraminer, Pinot Noir, others.
Sub-region 4
Golden Mile
1484 degree days.
Well-drained gravel, clay and sandy soils.
Common varietals: Merlot, Chardonnay, Gewurztraminer, and several other varieties.
Sub-region 5
Black Sage/Osoyoos
1492 degree days.
Soils are very deep sand.
Common varietals: Bordeaux varieties, Chardonnay, Syrah, others.
Climate
The Okanagan Valley lies in a rain shadow, between the Coastal and Monashee mountain ranges. This results in very low annual average rainfall. The area between Oliver and the US border is the northernmost tip of the Sonora Desert, which begins on the Baja Peninsula in Mexico.
Summers are generally very hot: average temperatures in July and August are warmer than in the Napa Valley. Summer daytime temperatures can reach 40°C, and are often above 30°C for several days in a row.
In the summer, there are long daylight hours and high light intensity due to the northerly latitude. In late June, daybreak is as early as 5 am and nightfall as late as 10:30 pm. This helps with prolonged daytime photosynthesis and grape ripening.
In summer there can be a four-degree average daily difference in temperature between Kelowna and Osoyoos. This results in a preference for red varieties in the south and white varieties in the cooler north. Precipitation is spread evenly throughout the year and wind is not a major concern.
The winters are cold and temperatures can drop below zero for long periods. Temperatures can fall to -25°C, but this is rare. The winter of 1978 was the last season severe enough to cause considerable vine kill. The region’s lakes moderate temperature extremes.
Soils
The soils, vineyards and local climates of each area have been mapped by PARC, and there are widespread differences throughout the valley. The southern part of the valley has deep sandy soils whereas the northern area around Kelowna is mainly composed of clay and gravel.
Topography
Several lakes run along the valley floor, the biggest of which is Lake Okanagan at 144 kilometres long and 3.5 kilometres average width. It is over 750 metres at its deepest point and is the source of much-needed water for irrigation.
The northern part of the Okanagan Valley, between Kelowna and Naramata, is narrow and marked by steep hillsides. The area for planting vineyards is limited.
The Naramata bench area (near Penticton) is marked by sloping vineyards in close proximity to the lake, with excellent exposure to the afternoon sun.
Higher-altitude vineyards, some of which are planted on slopes, mark the Okanagan Falls area. A few vineyards are planted on terraces.
From Oliver to Osoyoos, the valley fans out with flatter land in the Black Sage vineyard area. This is where the majority of acreage is planted, and is the area with the greatest potential for new development.