The mountain ranges have a very big influence on the climate, especially if they are larger mountain ranges, such as the Cascades. If the Cascades were west of Portland, instead of being on the east as they are, than Portland would have had significantly changed climate. By having the Cascades on the west, the rainfall would have fallen on their western side, windward side, as that would be the side facing the ocean. The eastern side of the mountains, where Portland would be located in this scenario, would be arid or semi-arid, as it will be in a rain-shadow. The rainfall will be stopped by the mountain, so Portland would have predominantly received dry winds, and very little precipitation. The continental influence would be dominant, so the summers would be dry and hot because of the warm and dry air masses coming from south, while the winters dry and cold because of the cold air masses coming from north..