German energy company RWE said a mild winter in Europe was to blame for a decline in its income, though CEO Peter Terium said he was optimistic nonetheless.

RWE said its recurring net income for the first quarter of 2014 was $1.15 billion, down 36 percent from the same time last year.

The company blamed an "extremely mild winter" for its poor performance so far this year. In the first three months of 2014, it sold 67 billion kilowatt-hours of electricity to the customers outside Germany, a 6 percent decline from the previous year. Gas sales, meanwhile, were down 19 percent because of weather-related issues.

Terium, the company's chief executive officer, said he was expecting a rebound for the rest of the year.

"Even though, as expected, the first quarter reflected the difficult environment in the energy sector, I can take positive stock nevertheless," he said in a statement Wednesday.

In March, the company agreed to sell off its oil and gas production unit DEA to an investment group led by Russian oil tycoon Mikhail Fridman for $7.1 billion.