Extreme Weather Now Drives Over Half of Canada's Catastrophe Losses as Heat Reshapes Insurance Pricing

From background noise to half the catastrophe pool

In Canadian insurance and reinsurance vocabulary, "primary perils" have traditionally meant the large, well-modelled events — earthquakes, major hurricanes, and headline-grabbing floods. "Secondary perils" have covered the rest: hail, severe convective storms, wildfire, drought, and prolonged heat. The Insurance Business report notes that heat waves in particular were historically treated as background noise because they rarely produce the concentrated property damage that trigger catastrophe designations. That framing has changed. The summit's reinsurance data showed secondary perils now generate 50 to 55% of Canada's natural-catastrophe loss pool, up from about 30% in the early 2000s.

The doubling is not a rebranding. It reflects real losses across multiple lines. Citing Swiss Re, the article notes that extreme heat can raise medical, life and workers' compensation claims, drive crop and livestock losses in agriculture insurance, and produce business-interruption and engineering claims when infrastructure or machinery is not designed for higher temperatures. In other words, a hotter climate does not just damage roofs. It reprices exposure across a portfolio, and portfolios are where premiums are set.

Earthquake remains Canada's single largest peak risk. That is worth acknowledging so the shift is not misread. But peak risk and portfolio composition are different questions. The catastrophe pool is what determines where reinsurance capital flows, what capacity insurers have available for consumer lines, and what price they need to charge to stay solvent through a bad year. When the composition of that pool moves this much, the downstream effects reach the homeowner's renewal notice.

Probabilistic modelling and postal-code pricing

The most consequential technical shift is the move to probabilistic modelling. Historical loss data alone becomes less useful when the frequency and geography of losses are changing faster than the historical record can accommodate. Insurers pricing property and casualty risk in heat-exposed regions are increasingly using models that generate loss distributions from physical and statistical assumptions about a changing climate rather than pattern-matching to the last decade of claims. That has a direct implication for households: premiums are not tied only to a specific home's claims history. They reflect the modelled loss potential of the neighbourhood, region, and portfolio the home sits inside.

The pricing granularity is now measurable. Statistics Canada's 2025 CPI methodology update documents that homeowners' insurance pricing is modelled at the Forward Sortation Area — the first three characters of a postal code — plus city, together with building value, neighbourhood traits, and distance from fire services. In practical terms, two homes on either side of a river or a rail line can face materially different pricing outcomes because their FSAs sit inside different risk clusters.

The premium effect is not theoretical. Statistics Canada reported that homeowners' home and mortgage insurance premiums rose 45.0% from December 2019 to December 2025, compared with a 21.0% rise in the all-items CPI over the same period. That study also identified 2024 as the costliest year on record for extreme-weather claims — $8.6 billion in catastrophic claims and $9.1 billion in total claims — and noted that every year from 2020 through 2025 ranked among the top 10 costliest. Six consecutive high-loss years is not the kind of run insurers absorb without repricing.

The landlord wedge that surfaced at the summit

The clearest new signal from the InSight Summit was the framing of landlord exposure. Real-estate risk professionals cited the previous summer's Toronto heat wave as a case study and pointed to reports of tenants pursuing legal action against landlords whose HVAC systems failed to keep units adequately cool. Summit panelists described that exposure as both a legal and a reputational risk that owners and operators need to plan for — rather than treating it as secondary to traditional perils like flood or wildfire.

That framing tracks the direction municipal regulation has already taken. The City of Toronto specifies that where a landlord provides air conditioning in a rental unit, it must be operated from June 1 to September 30 to keep temperatures at 26°C or below, and property owners must maintain existing air-conditioning systems in good working condition. As of June 1, 2026, some RentSafeTO buildings without in-unit cooling must also keep an indoor amenity space at or below 26°C. Combined with the June 2026 amendments to the Canada Occupational Health and Safety Regulations — which added detailed thermal-stress requirements, heat-threshold values, and humidex monitoring for federally regulated workplaces — the compliance and liability picture around heat is measurably more concrete than it was two years ago.

For landlords, the practical translation is that HVAC maintenance is no longer a comfort item to negotiate on year-end budgets. It is a coverage-and-liability question. A cooling system that fails during a heat wave in a jurisdiction with cooling maintenance obligations is a potential claim source across multiple lines: property, liability, and reputational. That does not mean every failure produces litigation. It means the risk profile of "we'll service it next year" is different than it was.

What this means for homeowners who are not landlords

For owner-occupiers, the heat-as-liability angle is narrower but not zero. Households that use short-term rental platforms, that host paying guests, or that have accessory dwelling units may sit in the same exposure envelope depending on lease structure and provincial regulation. And for anyone whose insurance already covers home-based business use, a heat-related failure that affects business operations or a client on premises can trigger business-side coverage questions rather than pure property questions. The general principle is the same: heat is now underwritten as an operational exposure with real financial consequences, not just a weather event.

Overland water, rebuild-cost adequacy, and the endorsement checklist

The catastrophe-loss shift lands on top of a coverage structure that many Canadian households have not fully audited. Government of Canada guidance is explicit that flooding is not typically included in a standard home policy, and Canadians often need policy endorsements or add-ons such as overland flooding, sewer backup, sump pump failure, or storm-surge-related protection depending on insurer definitions. The severity of the exposure is significant: floods are the most common and costly natural hazard in Canada, accounting for about half of all home insurance claims, with the average cost to repair a flooded basement estimated at more than $40,000.

The Financial Consumer Agency of Canada's guidance adds nuance for wildfire. Standard home insurance in Canada may cover fire, including wildfires, but usually does not cover outside-source flooding — extra flood coverage is typically sold as overland flood, inland flood, or enhanced water-damage coverage. That distinction matters because homeowners tend to conflate "climate risk" into one bucket. Wildfire is generally standard-covered. Overland water is generally not, and it is the endorsement most likely to be missing from an unaudited policy in a period when secondary perils drive half of catastrophe losses.

The second quiet gap is replacement-cost adequacy. Verisk Canada's Q1 2026 Reconstruction Cost Analysis reported a cumulative 24.8% rise in Canadian residential reconstruction costs over five years from a January 2021 base, including 23.8% in Ontario, and warned that price volatility has serious insurance-to-value implications when valuations are outdated or incomplete. A homeowner can renew every year at a higher premium and still be underinsured for reconstruction if the dwelling limit has not been reviewed against current rebuild costs. The Financial Consumer Agency of Canada notes that guaranteed building replacement can cover rebuild costs above policy limits if conditions are met — including carrying insurance for the full replacement cost and informing the insurer about value-adding improvements.

The three questions to bring to the broker

Given the pace of repricing, the practical action for homeowners is not to shop insurers reflexively but to ask three specific questions at renewal. First: is the insurer trimming exposure — reducing or non-renewing coverage — in the FSA where the home sits? A yes or a "we're re-evaluating" is a signal to explore the market before the notice arrives. Second: does the current policy include the endorsements for the perils most likely to affect the region — overland water in flood-exposed neighbourhoods, wildfire endorsements where the base policy has been restricted, sewer-backup and sump-pump add-ons for basement homes? Third: has the dwelling replacement limit been reviewed against current reconstruction costs, and would guaranteed building replacement close a gap if a total loss occurred?

For landlords, add a fourth: does the policy respond to cooling-related liability claims, and is HVAC service documentation current enough to support the coverage if a claim is filed? The summit disclosure suggests this exposure is going to be tested more often, not less.

The broader signal from the IBC summit is that Canadian insurers are treating the climate loss picture as a durable shift, not a cyclical bump. Probabilistic modelling, postal-code granularity, and landlord-cooling exposure are all downstream consequences of that framing. Homeowners who understand the pricing mechanism have a lever that pure comparison shopping does not offer — the ability to spot the endorsements and valuations that most often go stale, and to fix them before a claim exposes the gap.