The jet stream has some effect to, Wingman. It creates wind shear which avidly affects the growth and development of the storms. The jet stream forms as a result of increased temp differential over the tropics and the mid-latitudes. The jet stream is more noticeable in the winter because the temp differential is greater then in the summer. That's why storms that reach high-level's of the troposphere (aka Hurricanes) favor the summer time in the Atlantic basin.

Also to explain what Mr.Spock said about the water currents. The pacific high spins clockwise since the oreintation of the high, the high's winds drive cool sout pacific ocean water up to the Califoria Coast, that's why there water temp is so cold. It's the exact opposite in the atlantic basin as deep warm tropical water is brought forth from the tropics.