Canada Day is being blamed for the sudden spike in COVID-19 cases across the country this week, and between backyard barbecues, sharing drinks and seeing close friends for the first time in months, it's easy to imagine why.

First, let's look at the timeline.

Canadian health experts estimate that the incubation period of the virus is 14 days, which means that people could have contracted the virus at a Canada Day party, stayed asymptomatic, and unknowingly spread it to close contacts over a two-week period.

Those contacts would begin to show symptoms after about six days, which would explain why now — 21 days after Canada Day — the number of COVID-19 cases is rising.

Seems safe to say much of Canada is back to early exponential growth now; low numbers but R ~ 1.3. Atlantic and Northern regions remain quiet. pic.twitter.com/sWOwJrfGMh

— David Fisman (@DFisman) July 21, 2020

In British Columbia, more than 60 cases have now been linked to a cluster that began in Kelowna in early July, when visitors from other areas of B.C. and Alberta attended two private Canada Day parties.

In light of the news, Provincial Health Officer Dr. Bonnie Henry cautioned residents to remain vigilant.

"We do have the possibility of having explosive growth here in our outbreak, if we're not careful," Henry said at a press conference on Monday.

I hope everyone enjoyed their Canada day parties. https://t.co/NouV6JGVMq

— Lloyd Cosby🇨🇦🤟🏈🌍🔥♿ (@LloydCosby) July 21, 2020

Meanwhile, Ontario is reporting more than 200 new cases today, with more than half of them occurring in people in their 20s and 30s.

Although Ontario health experts haven't linked them to Canada Day parties, Premier Doug Ford implied at a Tuesday press conference that the case numbers were a result of Canadians attending private gatherings.

"Don't go to a party," he said. "It's simple."

Multiple Canadians have echoed Ford's words on social media, pointing to Canada Day parties specifically as the culprit behind the outbreaks.

"Concerning but not surprising with Canada Day street parties and festivities," an Ottawa resident wrote.

"To be honest, I don't think any of this relates to reopenings or announcements at all," another Ottawa resident wrote. "This was all triggered by Canada Day gatherings and July 1 [sic] signalling the start of summer for most."

WEAR A MASK. and to the idiots who had parties on Canada day this is your fault. we’re now seeing the consequences when we’re just finally moving into stage 3 of opening🤦🏼‍♀️ https://t.co/sYLutsLl3b

— michelle (@MichelleOkyo) July 21, 2020

Alberta has been especially hard-hit recently, with COVID-19 cases skyrocketing to 1,100 active cases this week, making it the province with the most active cases per capita.

"Yep, right on schedule," one Calgary resident wrote. "C'mon guys, you couldn't have just given up ONE Canada Day party? Really?!"

Prior to Canada Day, Provincial Health Officer Dr. Deena Hinshaw issued a message to Alberta residents urging them to celebrate the holiday at a distance where possible.

"If you are planning a private gathering in your backyard or your home, keep it within your cohort or stay outdoors," she wrote on June 30. "Avoid sharing food and drinks. COVID-19 will not take a break because it is a holiday."

Because they JUST became mandatory. Remember it takes up to 2 weeks to show symptoms. This rise in cases is possibly from Canada day weekend.

— Young Lady 🕷 (@Misasaur) July 21, 2020

Of course, Canada Day isn't the only reason that case numbers are rising across the country; a lack of masks, pandemic fatigue and reopening restaurants and shops could also be possible triggers for outbreaks.

On Monday, Chief Public Health Officer Dr. Theresa Tam reminded Canadians to "layer up" with face masks and hand sanitizer in the coming weeks.

"Just like hats, gloves, mitts, and a winter jacket, one item alone is not enough to protect you from the elements," she said in a statement. "If we think of public health measures as layers, the more layers we embrace as habits, the more we reduce our risk."