WASHINGTON — The National Restaurant Association’s Restaurant Performance Index ticked up slightly this past January as restaurant operators expressed optimism about the next six months even though store traffic was slow in January due to adverse weather conditions throughout the country.

For January, the R.P.I. stood at 100.7 compared to 100.5 for December.

“Restaurant operators are more optimistic about business conditions in the months ahead, which is also reflected in ramped up plans for capital spending,” said Hudson Riehle, senior vice-president of the research and knowledge group for the association.

The R.P.I. is made up of two components — the current situation index and the expectations index. During January the current situation index stood at 99.5, which was unchanged compared with December. Restaurant operators reported net positive same-store sales, but customer traffic was weak.

Restaurant operators reported a net decline in customer traffic for the second consecutive month. Thirty-three per cent of restaurant operators said they saw customer traffic growth between January 2013 and January 2014, while 50% reported a traffic decline. In December, 30% of operators reported higher customer traffic levels, while 46% reported a decline.

The expectations index was 100.8 in January, a 0.3% rise compared with December and the highest level it has achieved in seven months, according to the N.R.A. Restaurant operators are more optimistic about sales growth in the months ahead. Forty-one per cent expect to have higher sales in six months, compared with the same period in the previous year, up from 38% who reported similarly last month. Meanwhile, 11% of restaurant operators expect their sales volume in six months to be lower than it was during the same period in the previous year, while 48% expect their sales to remain about the same.

In comparison, restaurant operators are less optimistic about the direction of the economy. Twenty-nine per cent of restaurant operators said they expect economic conditions to improve in six months, while 20% expect the economy to worsen. The remaining 51% expect economic conditions to remain generally unchanged in the next six months.