Why would the climate differ between New York and Portland Oregon?

The main reason for the differences in the climate of New York and Portland are the ocean currents that have effects on them.

New York is under the influence of the warm Gulf current, which brings warm and wet air masses with it, thus making New York warmer and to receive large amounts of rainfall throughout the year.

On the other, Portland is under the influence of the California current which is not as warm, but also the Alaska current has its influence since it is in close proximity, so the waters are cooler and bring in cooler air masses, thus making the western coast colder than the eastern coast even though they are at pretty much the same latitude.