By Stephane Mahe and Manuel Ausloos
SAINT-MAGNE, France, Aug 11 (Reuters) - High temperatures and a worsening drought brought a high risk of new fires breaking out in southwestern France, officials said on Friday, even after an overnight reprieve held a monster wildfire that has been raging for days in check.
Firefighters from Germany, Romania and Greece were on the ground to help France battle the fire in the Gironde region - home to Bordeaux wine - as well as on other fronts, including in Brittany in the northwest, and more from across Europe were on their way.
The risk of new fires is "very severe" considering the weather conditions, the Gironde prefecture said.
"The day is likely to be complicated since temperatures continue to increase and humidity continues to drop, so obviously we remain vigilant and mobilised," senior local official Ronan Leaustic told a news conference.
Temperatures as high as 40 degrees Celsius (104 degrees Fahrenheit) were expected in the southwest, with high temperatures also expected across much of France, France's official weather forecast Meteo France said.
The heatwave - officially France's third this summer - was set to ebb on Saturday and end on Sunday with storms, it said.
Some 7,400 hectares (18,000 acres)of forests have gone up in flames in Gironde, and 10,000 people have been evacuated.
Wildfires have broken out across Europe this summer as successive heatwaves bake the continent and renew the focus on climate change risks to industry and livelihoods.
A huge wildfire raged throughout the night and into its seventh day on Friday in central Portugal, where more than 1,600 firefighters backed by nine waterbombing aircraft were combating the blaze that has destroyed about 15% of the Serra da Estrela national park.
After starting in the Covilha area on Saturday, the fire has spread to several neighbouring councils, burning around 15,000 hectares (37,000 acres) overall.
Meanwhile, water levels on the river Rhine in Germany have fallen again, with some vessels no longer able to sail, shipping operators and brokers said.
And British households were facing new water usage restrictions, with parts of England likely to declare a drought as the government, environment officials and water companies meet to discuss the prolonged hot and dry weather.
Politicians across the continent are evaluating the impact.
"This fire season this year is far from over," Pascal Martin, a centrist French senator and former firefighter told Europe 1 radio.
"Now though two lessons have to be learned, which is that the fires are extending both geographically and over time, no longer only in the south, but in the entire country, even in the Jura and in Brittany, and no longer just in the summer months."
(Reporting by Myriam Rivet, Manuel Ausloos, Stephane Mahe, Geert de Clercq, Farouq Suleiman, Andrei Khalip and Michael Hogan; Writing by Ingrid Melander; Editing by Alison Williams)