The summers on the coasts of northern California and Oregon are considered as dry.
Even though both northern California and Oregon are pretty rainy places for most of the year, in the summer that is not the case. The summer months bring higher temperatures and lots of wind, but the rain significantly decreases during this period. The rain in the summer is much rarer and it is usually a light short rain.
The US and Brits wouldn't have access to Russia to send supplies and Russia is cold so both countries would have to wait till spring to counter-attack.
