Aug 1 (Reuters) - Utility firm Alliant Energy ( LNT )

missed Wall Street estimates for second-quarter profit on

Thursday, hurt by higher operating costs and weak cooling demand

earlier in the quarter.

Madison, Wisconsin-based Alliant serves roughly 1 million

electric and 425,000 natural gas customers in Iowa and

Wisconsin.

The company said it saw lower-than-normal heating degree

days, a measurement used by utilities to gauge power demand,

during the quarter, while its residential gas deliveries also

fell by 11.8%.

Alliant also saw a 9.9% increase in operating expenses

from a year ago, driven by an asset impairment charge for its

Interstate Power and Light Company units' Lansing power

generating station in Iowa.

It reaffirmed its full-year earnings forecast of $2.99 -

$3.13 per share.

The company reported adjusted earnings of 57 cents per

share, missing estimates of 64 cents per share, as per LSEG

data.