Iberia power at month-low on wind power surge

* Spain day-ahead base 43.01 euros/MWh, down 10.61 euros

* Demand steady despite cold snap

* Winds seen higher still on Friday

MADRID, Feb 1 (Reuters) - - Iberian power prices fell to a month-low in wholesale trade on Wednesday as dealers saw output from costly gas- and coal-fired generators diving 40 percent the next day due to a steep increase in output from Spain's wind sector.

Demand in Spain was seen flat on Thursday over Wednesday, although it has risen by a moderate 2.6 percent over the past week due to a wave of cold weather affecting much of Europe.

National grid operator REE forecast wind parks in Spain, which accounts for 85 percent of trading in the Iberian Electricity Market (Mibel), would raise production to as much as 11,200 megawatts from 7,000 MW on Wednesday afternoon.

Mibel's spot unit, OMIE, fixed the widely watched day-ahead "pool" price at 43.01 euros ($56.30) per megawatt-hour, down from 53.62 euros previously and its lowest weekday level since Jan. 2, when many Spaniards were still on holiday.

Producers' group AEE estimates each 1,000 MW of wind power included in OMIE's daily auction matching offers from generators and bids from distributors cuts the pool price by an average of 1.70 euros/MWh.

Looking ahead, producers predicted wind power would rise higher still on Friday, which in the absence of other factors could haul down the pool on Thursday.

Also weighing on prices was abundant supply of nuclear power, with all eight of Spain's reactors working normally and generating 7,479 MW in all, or 18.3 percent between them, according to REE and the CSN regulator. ($1 = 0.7639 euros) (Reporting by Martin Roberts)