Think things couldn’t get worse for condominium developers? Think again.

International buyers are turning away from condominiums in the United States. The global economic downturn combined with the new strength of the U.S. dollar compared to other currencies has cut into the buying power of these would-be buyers, making condos here less attractive.

Condo developers have come to rely on internationals. In markets like Miami, as many as half of the condos sold last spring were to Latin American buyers purchasing second homes, according to estimates by local experts. In Manhattan, local experts said as many as a quarter of the condo and co-op apartment buyers came from outside the United States. Some New York City developers even opened sales offices in Europe.

However, in November, the dollar was the strongest it has been in years against a range of currencies from the euro to the British pound to the Colombian peso. It’s impossible to know how long the dollar’s strength will last, but as long as it continues, international buyers will have another reason not to invest in condo markets here.