Bars and restaurants in the ByWard Market are feeling the pinch after sweltering temperatures melted business on what should have been one of the busiest days of the year.

Temperatures on Canada Day climbed quickly, reaching 34 C by noon, according to Environment Canada.

By mid-afternoon, the humidex made it feel more like 47, driving many revellers to stay indoors.

Along Clarence Street, many restaurant managers said it was one of the slowest Canada Days they'd ever seen, with some noting a significant drop in revenue compared to last year.

Michelle Melanson, bar manager at Patty Boland's Irish Pub and Eatery, said revenues were down approximately 50 per cent.

"I've been here for about 29, 30 years," she said. "I've worked every Canada Day and this is the worst Canada Day in history."

Lindzy Thompson, general manager of the King Eddy, is also a ByWard Market veteran, having spent the last 13 years working on the holiday.

She said the streets were pretty bare compared to the holiday in past years.

"It was by far the slowest one I've ever seen," she said. "Fortunately, we're 24 hours, so we made it up in the evening and the overnight."

Heat causes drop in foot traffic

Many managers blamed the drop in business on fewer people walking the streets because of the high temperatures.

"There's nobody walking around," said Michael Gibson, general manager of the Blue Cactus. "You couldn't walk around. So your walk-up crowd was really gone because it was too hot."

The restaurant saw between a 30 and 40 per cent drop in business compared to last year, Gibson said.

Jeff Hodgins, the general manager of the Clocktower location in the ByWard Market, said the drop in customers had them sending some of the serving staff home.

"We did have to cut some people," he said. "We had eight servers on and then we ended up sending three home early."

Even Parliament Hill saw a drop in attendance. Officials said around 6,200 people crowded onto the hill at around 11:15 a.m., but that number dropped to approximately 3,500 people a mere two hours later.

Misting stations helped cool down Parliament Hill partiers. (Kimberley Molina/CBC)

Andrew Campbell, assistant deputy minister for Canadian Heritage, said that's far below normal numbers.

"Normally we get between 15,000 and 20,000 during the noon day show," he said, pinning most of the blame on the weather.

"During the day, the turnout was lower principally because of the heat," he said. "It was oppressive during the middle of the day."

Though daytime attendance at official events was down, paramedics had a busy weekend. By Sunday night, just over 100 people had been treated for heat-related illnesses, while 18 were taken to hospital.

Long weekend a bust?

It wasn't just on Canada Day that business was affected. Temperatures remained high the entire long weekend, making business sluggish for at least three days, Melanson said.

"Friday was affected, Saturday was affected," she said. "Hopefully it's not the same next year."

Even at the beginning of the weekend, temperatures reached the low 30s, making patio dining tough to stomach for some, especially the elderly and families with young children, Gibson said.

However, despite the sticky heat of the day, many managers said business picked up again in the evenings.

Parliament Hill also recorded normal attendance numbers during the evening events, with around 30,000 people turning out, Campbell said.

"It seemed like people waited for the sunset and then they came out," Melanson said. "So it was still hot, but not as hot."