Iberian spot power gains on weaker winds

* Spain day-ahead 44.28 euros ($57.16)/MWh, up 2.12

* Cal-11 44.80 euros/MWh (OTC)

MADRID, July 27 (Reuters) - Iberian spot power gained on Tuesday as relatively cheap supplies of wind power were seen down for a second day and hotter weather augured increased demand for air conditioners and fans. Omel, the Spanish-based spot exchange, set the day-ahead "pool" price -- a reference for over-the-counter trading -- at 44.28 euros per megawatt-hour, up from a rate of 42.16 euros fixed on Monday.

The pool is now 4.8 percent below a 2010 high of 46.51 euros/MWh set on July 20, when Spanish wind parks -- the world's fourth-largest -- were becalmed and temperatures rose above average.

Grid operator REE (REE.MC) predicted wind power in Spain would dip to a minimum of 2,500 megawatts on Wednesday from 3,000 MW on Tuesday afternoon.

Also bolstering prices were Met Office forecasts that temperatures in Madrid, Iberia's biggest city, would rise to 38 degrees Celsius on Wednesday, from 36 degrees on Tuesday.

Looking ahead, producers expected wind power to soar as high as 10,000 MW on Thursday, which may weigh on the pool when it is next published on Wednesday morning.

In the over-the-counter market, traders reported the benchmark calendar-year 2011 changing hands at 44.80 euros/MWh, down 0.35 euro from late dealing on Monday.

All eight of Spain's nuclear power stations were running normally and feeding 7,315 MW between them to the grid, or 17.6 percent of total demand, according to data from REE and watchdog CSN.

In other news, the latest official data showed Spanish hydropower reserves fell due to dry weather last week but were still comfortably above average. (Reporting by Martin Roberts, editing by Jane Baird)