Is 72 hours of supplies enough? What 93 nationwide power outages show

This week a post on X spread as breaking news: Public Safety Canada wants people ready to go at least three days without running water or electricity. The advice is years old, and no known event is behind it. It does raise a question we can answer with data: how often is three days actually enough? For nationwide power outages since 2022, the answer is about nine times out of ten. The exceptions show who should plan for longer.

What was actually said

Canada changed nothing. CBC reported that the agency is keeping its longstanding advice. A spokesperson said Canadians are encouraged to "be ready to take care of themselves and their households for a minimum of 72 hours during an emergency". That is the same figure the government's emergency kit page has long used.

The UK did start something new. On 22 October it launched Be Ready, a campaign asking households to prepare for three days of disruption to "power, water, phones and the internet". The government says France, Ireland and the Netherlands use the same three days.

Nobody is reacting to a shared threat. CBC found "no indication that any of those announcements were co-ordinated or are connected to a particular expected event", though the timing "has set off some speculation online". We have a running list of those rumours.

How long nationwide power outages really last

Cloudflare Radar has logged 93 power outages listed as nationwide since January 2022, in 53 countries and territories. We keep them all, so we can simply measure them. The typical one (the median) lasted 9 hours.

So 74 of the 93 were over within a day, and 85 within three days. Spain and Portugal's huge blackout in April 2025 lasted about 13.5 hours on this measure.

The eight that ran past three days

• 252 hours Puerto Rico, September 2022: Hurricane Fiona
• 226 hours Saint Vincent and the Grenadines, July 2024: Hurricane Beryl
• 166 hours Jamaica, October 2025: Hurricane Melissa
• 108 hours Guam, July 2026: Super Typhoon Bavi
• 96 hours Grenada, July 2024: Hurricane Beryl
• 84 hours Cuba, October 2024: the national grid disconnected
• 75 hours Cuba, September 2026: nationwide power outage
• 74 hours Puerto Rico, April 2022: fire at the Costa Sur power plant

Every one of them is an island. Of the 19 outages that lasted more than a day, 18 were on islands; the exception was Kenya in August 2023 (29 hours). Five of the eight followed a hurricane or typhoon. Our reading is that a small grid with no neighbour to lean on has little to fall back on when its lines or plants are damaged. The numbers show the pattern, not the reason. Cuba alone accounts for 12 of the 93, as its ageing grid keeps failing.

Why this doesn't settle it for Canada or the UK

Neither country appears in these 93 outages, not once. That doesn't make them safe from long power cuts. It means their long cuts are local: storms break lines in one region, and the country as a whole carries on. These three show what that looks like.

• Storm Arwen, UK, November 2021 Nearly 1 million homes lost power. 82% were back within 24 hours, yet nearly 4,000 homes went more than a week without it.
• Hurricane Fiona, Nova Scotia, September 2022 Average restoration time was just over 100 hours, about four days. In every region it took at least two weeks to reconnect everyone.
• Ice storm, Quebec, April 2023 At the peak, 1.1 million Hydro-Québec customers had no power. Six days later, more than 19,000 were still waiting. In Montreal, 180 people were treated for carbon monoxide poisoning, so never run a generator or fuel heater indoors.

Arwen's 82% is close to our 80%: most people got power back fast, and a few waited far longer. Fiona was harder, with only about half of customers back within 48 hours of crews starting work. This is why Public Safety Canada calls 72 hours "a minimum recommendation". One expert CBC spoke to, Suzanne Bernier of Disaster Recovery Institute Canada, suggests seven days of supplies.

The lights aren't the only thing that goes

The UK campaign names phones and the internet for a reason. In the Iberian blackout, IODA's internet signal fell to 30% of normal in Spain and 18% in Portugal. Mobile sites run on backup batteries, typically sized for around eight hours, so a long power cut can take the phone network with it.

It also works without any power cut. When Rogers failed in Canada in 2022, Interac debit payments stopped nationwide and some people could not reach 911. The electricity never went off.

What to take from this

1. Treat 72 hours as the floor. It covers most outages. Plan for longer if you live on an island, in a storm zone or at the end of a long rural line, or if you depend on powered medical equipment.
2. Count your water. Canada says about 4 litres per person per day, and the UK 3 litres. For three days, that is 12 or 9 litres each.
3. Plan for no phone and no card. Keep a battery or wind-up radio, a charged power bank and some cash. Canada's list also suggests a corded phone.
4. Use your own country's list. Canada and the UK both publish one. You can follow reports for your area on our power outage pages.

This is not a warning: we know of no coming outage. Blackout Map is an independent monitor, not an official source. We show what we measure and never predict outages.

How we counted

These are outages big enough to show up in internet traffic, so this is a list of major events, not of every power cut. Each country counts once per outage, so Spain and Portugal count as two. Nationwide doesn't always mean every home lost power. Cloudflare's end time describes the country's internet traffic, not the moment the last home was reconnected, and many end times are rounded, so the line at 72 hours is not exact: one Cuban outage in November 2024 stopped just short, at 70.5 hours. Numbers as of 6 November 2026.

Sources

• CBC News: Ottawa wants us all to have emergency supplies for 3 days
• Government of Canada: making an emergency kit
• GOV.UK: households encouraged to take small, simple steps
• UK Defence Journal: households asked to prepare for three days of disruption (3 litres a day)
• Cloudflare Radar Outage Center (CC BY-NC 4.0)
• IODA, Georgia Tech
• Ofgem: full report on the response to Storm Arwen
• CBC News: breakdown of Nova Scotia Power's Fiona outage statistics
• CBC News: thousands of Quebec residents still without power 6 days after ice storm
• NPR: Puerto Rico plunged into darkness after a power plant fire
• Telco Magazine: telcos disrupted by Iberian power outage