* French spot for Tuesday at 63 euros
* French demand to jump by 2.5 GW to Tuesday
* Forward prices down along with coal, CO2, oil, gas
FRANKFURT, Oct 10 (Reuters) - European power prices for day-ahead delivery on Monday traded at their highest levels since January as demand increased due to colder weather, but they were below new spot price highs hit late last week.
"The underlying picture of colder weather and lingering doubt about the robustness of French nuclear supply underpin the market, although we're down from last week," one trader said.
France's spot power price for Tuesday delivery, at 63 euros ($70.57) a megawatt hour, was 17 euros up from Sunday's close, but 10.25 euros down from the close of the Monday delivery position (day 3) last Friday.
The position is at the highest level seen for day-ahead since January 20, which was a typical winter day spike, although to date, there are no severely cold temperatures.
The German contract for Tuesday, at 38.7 euros/MWh, was down from 46 euros paid for Monday last week, but also at the highest day-ahead level since Jan. 18.
Prices for French week ahead and two-week ahead delivery eased from their previous settlements by 24 and 18 percent, respectively.
Both spot and forward electricity contracts rose more than the last fortnight on worries that France, which depends on nuclear for 75 percent of its demand, could face tight supply on increased outages and output cuts from its 58 nuclear reactors.
Thomson Reuters data showed that French power demand will rise by 2.5 gigawatts (GW) to 56.8 GW on Tuesday, compared with Monday levels, while Germany's demand will rise by 1.6 GW.
German solar availability on Tuesday will be down 0.7 gigawatts (GW) from Monday, reaching 3.3 GW, and wind supply will more than halve to 5.4 GW.
Along the forward power curve, prices fell alongside those in markets that are related to power.
The German benchmark Cal'17 year-ahead baseload contract was down by 45 cents at 30.05 euros, while the less liquid equivalent French contract dropped by 1.9 euros to 39.6 euros /MWh.
Front-year EU carbon allowances fell 2.1 percent to 5.57 euros a tonne.
Coal, which accounts for more than 40 percent of German power generation, fell 4.3 percent to $63.7, reversing a recent rally.
The current 2017 price represents a one-week low, but levels above $63 were last seen 18 months ago.
In eastern European power, the Czech year-ahead 2017 contract shed 70 cents to 30.60 euros/MWh, while the day-ahead spot fell 3.35 euros to 50 euros/MWh.
$1 = 0.8928 euros Reporting by Vera Eckert,; Editing by Louise Heavens