January's severe weather caused a record decline in the number of new homes started in the month.

Figures released yesterday by the Bureau of Census showed that privately owned housing units were started at the seasonally adjusted rate of 1,375,000 units in January in contrast to the revised annual rate of 1,884,000 units in December, a drop of 27 per cent. However, the January figure is still 9 per cent higher than the rate of 1,259,000 starts recorded in January 1976.

A breakdown of the Census statistics showed that the January rate of seasonally adjusted starts of single houses was 1,029,000, compared with 1,331,000 in December. The January rate for units in apartment buildings (with five or more units) was 253,000 compared with the December figure of 430,000. Units in buildings for two to four families totaled 93,000 starts in January.

Most of the January drop in new houses started occurred in North Central and Northeast states, according to Michael Sumichrast, chief economist of the National Association of Home Builders. He said that reports from major population centers showed that residential housing starts were down about 62 per cent in the North Central area and 41 per cent in the Northeast.

"Ninety per cent of the decline in January was due to the weather and the rest to a falloff in starts of subsidized housing units for low-to-moderate-income renting families," Sumichrast added.

In this Washington area, estimates are that the pace of new residential permits filed in January declined 45 per cent from the 1,702 in December. In January, a year ago, 1,020 permits were filed in this area, compared with the 938 permits in the month just past.

While the recent freeze delayed almost all "outside" housing work on foundations, masonary, roofing and siding for about six weeks, builder-developer Milton E. Kettler said that the weather did provide one good paradoxical twist:

"We couldn't build but we did sell." He said that sales in the first five weeks of 1976 at varied Kettler communities totaled 21 units in contrast to 50 contracts taken in the first five weeks of this year.

Other area home builders also reported better than usual sales in January.