OTTAWA - Sarah McLachlan was belting out her one of her haunting ballads with a little too much gusto ahead of her headlining performance on Parliament Hill for Canada's birthday bash when she stopped in mid-song for a bilingual self-critique.

"Lots of cheese," she quipped to the few dozen or so tourists and technicians watching her rehearsal. "Beaucoup de fromage."

The British Columbia songstress will scale back the cheese factor and amp up the entertainment Wednesday during a performance celebrating the country's 142nd birthday.

She'll be joined by hip-hop artist K'naan, the indie popsters Said The Whale, native dancers and an eclectic mix of other artists that will use the Peace Tower as their backdrop.

There was still plenty of work to do Tuesday before the partying began.

A noon downpour in the nation's capital drenched the maple leaf-inspired stage as a backup band rehearsed an instrumental O Canada.

The Snowbirds, Canada's military aerobatic demonstration team, soared over Parliament Hill three times as technicians pushed rainwater off the stage with large squeegees.

The rain gear may come in handy on Wednesday. Forecasters are predicting showers just as the performers start their show.

McLachlan staged a casual preview of her performance. Dressed in baggy knee-length cargo shorts with a beige cardigan thrown over a grey tank top and her auburn tresses pulled back into a ponytail, McLachlan strummed an acoustic guitar and belted out verses of her haunting hit, Building a Mystery.

The rain broke moments later and the warm midday sun flooded the stage.

"Ah, there's the sunshine," the singer observed.

A spokesman for the National Capital Commission, which is organizing the festivities, rhymed off a raft of milestones to be celebrated. Canada's 142nd birthday. New Brunswick's 225th anniversary as a colony. Ten years since Nunavut was carved out of Canada's frozen Arctic tundra. One hundred years since the first powered flight in Canada. Newfoundland and Labrador's 60th year in Confederation.

"So, lots to celebrate in addition to the unique values we share as a nation," spokesman Guy Laflamme said.

Prime Minister Stephen Harper released his own Canada Day message in which he reflected on a tough past year while noting the country has fared better than most during the worldwide economic downturn.

"We celebrate the most peaceful, prosperous and enduring democracy the world has ever known. We reflect on the wisdom of our ancestors who built this great land. And we give thanks to those brave Canadians who risk their lives to defend us, here and around the world," he said.

"We must never forget that our country, our way of life, did not happen by accident. We are a product of diverse peoples committed to common values, a country that cherishes freedom, democracy and justice, a country proud of our past and confident in our future."

Gov. Gen. Michaelle Jean singled out Canada's youth in her birthday wishes.

"In every city and every community, from Moncton to Fort Simpson, Rankin Inlet to Montreal, Vancouver to Trois-Rivieres, young people are redefining our world in a spirit of greater solidarity," she said in a statement.

"These youth, whom we relegate far too often to the future, as though they have nothing to offer the present, are in fact, day after day, our most powerful antidote against inaction and indifference. So let us salute our youth and stand not behind them, nor in front of them, but with them in our shared desire to explore every possibility between us and in each of our lives."