* Spain day-ahead base 31.20 euros ($44.71)/MWh, up 0.17
* Cal-10 up 0.45 at 40.05 euros/MWh (exchange)
MADRID, Dec 21 - Iberian spot power prices hovered near year-lows on Monday as a rise in supplies of cheap wind power offset the impact of a cold snap, dealers said.
The day-ahead price fixed by the Omel exchange for Tuesday was 0.13 euros per megawatt hour above the rate published for Monday, which was the lowest for a working day in 2009, a sign many offices and factories have closed for the festive season.
Spain's Met office issued weather warnings for half of the country, while snow covering much of the country delayed trains and blocked roads.
Data from national grid operator REE (REE.MC) showed that wind parks in Spain -- the world's third-most productive -- were supplying 24.7 percent of the country's electricity, up from 12 percent on Friday.
Looking ahead, wind power was seen fading on Tuesday and Wednesday which may bolster spot prices, but demand was seen falling further due to the approaching Christmas holidays and expectations of milder weather.
Forwards meanwhile gained in reponse to firmer oil prices, but were still close to year-lows because weak gas prices have cut estimated costs of generating power in the months ahead.
Calendar-year 2010 was up 0.45 euros/MWh at 40.05 euros on the Omip exchange, which compared with a minimum for the year of 38.40.
Spain's grid is still short of 2,000 MW of nuclear power because the Almaraz I plant is refuelling and not due back until this week, at the earliest, and Asco I reactor is offline for maintenance until the New Year.
The remaining six nuclear plants were producing 5,340 MW, or 13.5 percent of the generating mix, according to REE (REE.MC).
Spanish power stations were meanwhile emitting 8,950 tonnes per hour of carbon dioxide. (Reporting by Martin Roberts; Editing by Keiron Henderson)