March 5 (Bloomberg) — Service industries in the U.S. expanded in February at the slowest pace in four years, showing the biggest part of the economy was struggling as harsher weather weighed on consumers and businesses.

The Institute for Supply Management's non-manufacturing index fell to 51.6 last month, lower than any forecast of economists surveyed by Bloomberg and the weakest since February 2010, from January's 54, the Tempe, Arizona-based group said today. A gauge above 50 shows expansion. The median estimate in a Bloomberg survey of economists was 53.5.

Scant momentum in the pace of hiring, limited income gains and rising mortgage rates are holding back consumers while unusually severe weather also limited retail sales and factory activity earlier this year. More progress in the housing market and faster job gains might be needed to propel the expansion in the first half of 2014.