After rising for two straight weeks, mortgage rates this week resumed a downward trajectory to come in at their lowest levels since May.

The average rate on a 30-year fixed-rate mortgage was 6.60%, down from 6.66% the prior week, data from Freddie Mac showed.  The average rate for 15-year fixed-rate mortgages continued its pattern of decline, falling for the fifth straight week to hit 5.76%, down from last week’s 5.87% rate. Both rates are at their lowest levels since the spring.

“This is an encouraging development for the housing market and in particular first-time homebuyers who are sensitive to changes in housing affordability,”  said Sam Khater, Freddie Mac chief economist. “However, as purchase demand continues to thaw, it will put more pressure on already depleted inventory for sale.”

There is some hope that more housing supply may be coming, with an increase in building permits indicating that more housing construction is planned, while housing starts in December were up more than 7% over the prior year. 

The lower mortgage rates, along with an improved home-building environment, could help improve the outlook for beleaguered homebuyers in one of the most unaffordable housing markets in decades.