Dakota, South Dakota, Minnesota, Iowa, Wisconsin and northern Illinois. Pacific Northwest The Pacific Northwest has an oceanic climate. The climate is wet and cool in autumn, winter, and spring, and stable and dry in the summer months, especially July and August. On average, the wettest month is typically November or December; the driest, July. In the summer months, average highs in cities like Seattle and Portland are from 70 to 75 °F (21 to 26 °C) with lows from 50 to 59 °F (10 to 15 °C), while in winter daily highs are from 40 to 45 °F (4 to 9 °C) and overnight lows from 30 to 38 °F (−1 to 4 °C). In winter, the Pacific Northwest (especially coastal districts and other areas west, i.e. on the prevailing windward side, of the Olympic and Cascade mountain ranges), experiences a mostly overcast, wet and cool climate, but without severe cold like that found in the interior northern U.S. (i.e. Minnesota/North Dakota). At lower elevations, winter precipitation falls mostly as rain. However, snow does occur even at the lowest elevations, primarily when Pacific moisture interacts with cold air intruding into the Pacific Northwest from western Canada (i.e. Alberta and interior British Columbia). Summers in the Pacific Northwest are generally cool, especially along the coastline. The Great Basin and Columbia Plateau (the Intermontane Plateaus) are arid or semiarid regions, with high summer temperatures in the 90s to occasionally over 100 at lower elevations (e.g. at Boise, Idaho), with annual precipitation averaging less than 15 inches (380 mm) as a result of the rain shadow of the Sierra Nevada and Cascades. Both coastal and interior areas of Oregon and Washington, and southern Idaho, have a wet-winter, dry-summer precipitation pattern, but traveling eastward into Montana and Wyoming, this transitions progressively (for example, at Missoula, Montana) toward relatively drier winters and a May and eventually June precipitation maximum, the latter characteristic of the Northern Plains and much of the upper Midwest (i.e. both Dakotas, Nebraska, Iowa and Minnesota). Alaska The climate in Juneau and the southeast panhandle is a mid-latitude oceanic climate (Köppen Cfb). The climate in the extreme north of Alaska is what would be expected for an area north of the Arctic Circle — it is an Arctic climate (Köppen ET) with long, very cold winters and short, cool summers. Akclimate.org says the following: "The altitude above sea level influences the climate