Simon Taylor, of Stone, Vine & Sun in Winchester, says the dollar's weakness against the pound means he will be able to get better value for money on wines from the two states.
He said: "I'm being opportunistic. A $30 wine used to look expensive, but now it only costs £15. And if the wine's good enough then there's a great opportunity for me to make a bigger margin here.
"The wines are never going to be big. They're for a niche market, but I have always personally liked them. The Bordeaux blends coming out of Washington state can be very good," he added.
Taylor said he is also making more money on wines from Chile and Argentina because he can buy wine from these countries using US dollars - and make a saving.
" If you can get the right wine and your customers really like it, then you'll make money even if the exchange rate changes," he said.