Fall and Winter 2026-27 Rain Outlook for Metro Vancouver

What It Means for Your Parking Lot and Drains

Short answer: a strong El Niño is building, and ECCC expects a mild winter on the BC coast. Mild means more rain and less snow, and El Niño winters often run a bit drier overall. But Vancouver's own records show El Niño winters still bring big rain. Two of the three strongest El Niños on record gave the airport one of its 15 wettest rainy seasons since 1950, and the wettest single day in that whole span, 89.4 mm on Christmas Day 1972, came during a strong El Niño winter.

The near term looks wet too. As of October 21, AccuWeather's extended forecast for Vancouver  showed a 55 to 75% chance of rain every day from October 30 to November 4, right as the leaves come down.

If your property has catch basins that haven't been cleaned since last winter, the window to do it is now, before leaf drop and the first big atmospheric river line up on the same week.

What the 2026-27 outlook says for Metro Vancouver

Environment and Climate Change Canada (ECCC) produced its latest seasonal forecast on September 30, 2026. For October to December 2026, the map leans toward above normal precipitation along the BC coast and offshore waters, and toward below normal precipitation in the southern Interior. For November 2026 to January 2027, the Lower Mainland sits in the "equal chances" zone. In plain terms, ECCC's models don't see a strong wet or dry tilt for us.

Temperature is a clearer story. ECCC's Nathan Gillett told the Vancouver Sun  in October that there is a high chance of a mild winter on the BC coast, and that BC is expected to get less snow than normal.

The main reason is El Niño. On October 8, 2026, the US NOAA Climate Prediction Center  said El Niño was still strengthening, with a strong to very strong event likely through January to March 2027. Its October 15 seasonal outlook  favours a warmer than normal winter across the Pacific Northwest. NOAA's wetter West Coast signal only reaches as far north as the Oregon coast.

What history says about El Niño winters in Vancouver

A strong El Niño usually tilts the BC coast warmer and often drier. ECCC's Marko Markovic said as much  in September, and added that even a super El Niño doesn't guarantee big impacts. But drier on average is not the same as no big storms, and Vancouver's own records show why.

We pulled every rainy season (October to March) at Vancouver International Airport since 1950 from ECCC's historical climate data  and matched them to NOAA's record of strong El Niño years, those with an Oceanic Niño Index  peak of 1.5 or higher. Here's what those nine winters looked like.

What the record says:

• Barely drier on average. These nine winters averaged 828 mm of rain, about 1.5% less than the 841 mm average across all 75 seasons, with 4.6 heavy rain days per winter versus 5.1.
• Two of the three strongest were very wet. 2015-16 and 1982-83 both ranked among the 15 wettest rainy seasons since 1950. The third, 1997-98, was on the dry side.
• The biggest single day came in an El Niño winter. The airport's wettest day since 1950 was 89.4 mm of rain on Christmas Day 1972.
• Heavy days still showed up. Eight of the nine winters had at least two days with 25 mm or more. Those are the days that test a catch basin.

So the honest read for 2026-27: probably mild, possibly a little drier, with real odds of a few very wet days. Plan for a normal rainy season.

Atmospheric river season: why October to January matters

An atmospheric river is a long, narrow band of moisture that can dump a lot of rain in a short time, as ECCC describes them. They are a normal part of BC weather, not something that only shows up in bad years.

Recent examples on the South Coast:

• October 2024: ECCC warned of an atmospheric river bringing up to 200 mm of rain  in the wettest spots over a weekend, with up to 70 mm across most of the region, including Metro Vancouver. The airport logged 67.1 mm on October 19, its wettest day of the year.
• January 2026: ECCC issued a rainfall warning for 75 to 100 mm in Metro Vancouver, with more on the North Shore and Burnaby Mountain.
• November 2021: the airport recorded 312.4 mm for the month, the wettest month in our 10-year data pull.

We pulled 10 years of daily rainfall from ECCC for Vancouver International Airport (2016 to 2025). There were 67 days with 25 mm or more of rain. 49 of those 67 heavy days, about three out of four, fell between October and January. That's the season a blocked catch basin gets tested.

What heavy rain does to a blocked drain

A catch basin works like a funnel with a trap at the bottom. Water flows through the grate, sediment and debris settle in the sump, and water leaves through the outlet pipe. When the sump fills with grit or the grate is matted with leaves, the water has nowhere to go.

In a light shower, you might not notice. In a 25 mm day, a plugged basin backs up fast. Water spreads across drive lanes, fills low spots, and sits against curbs and building entrances until the storm passes or someone clears the grate.

Leaf drop: the October and November problem

The City of Vancouver says it plainly: heavy rain plus fallen leaves clogs catch basins  and causes flooding and ponding. The city has about 45,000 catch basins of its own and receives over 1,000 calls a year about flooding at catch basins.

The city's advice for timing applies to private lots too. Check basins before and after heavy rain, and when trees have shed their leaves. On a strata or commercial site with mature trees, that usually means one cleaning before leaf drop and a check once the trees are bare.

One more point from the city that applies to landscapers: never rake or blow leaves onto paved areas that drain to catch basins.

What a blocked catch basin really costs

We're not going to quote a dollar figure here, because it depends on the site. But these are the costs that matter most on a strata or commercial lot.

Pooling and access problems. Ponded water at entrances, accessible stalls and loading areas is the first thing tenants notice and the first thing they call about.

Ice in December and January. Vancouver's airport averages about 12 nights at or below 0 C in December and about 10 in January ( ECCC 1981 to 2010 normals). Water left standing by a plugged drain can freeze overnight into a sheet of ice right where people walk. For the snow and ice side of the season, see the Vancouver snow forecast  and the Winter 2026-27 Outlook for the Pacific Northwest  from Invictus Snowfighters.

Slip and fall risk. Under BC's Occupiers Liability Act, an occupier must take reasonable care to keep people reasonably safe on the property. Keeping drains working and fixing known ponding is part of showing reasonable care. This isn't legal advice; talk to your lawyer or insurer about your site.

Strata duties. Under the Strata Property Act, section 72, the strata corporation must repair and maintain common property. Parking areas and their drains are often common property; your strata plan and bylaws will say for sure.

Municipal bylaws. Each city in Metro Vancouver has its own drainage bylaw. Surrey's Stormwater Drainage Regulation and Charges By-law, for example, includes rules against fouling the city's drainage system. Sediment and oil washing out of a neglected private basin can become a bylaw issue. Check your own city's bylaw.

Asphalt damage. Water is hard on pavement. A National Academies study  notes that water gets into asphalt through cracks and joints, and that debris built up at the pavement edge stops water from draining away, weakening the layers underneath and shortening pavement life. Standing water over winter often shows up as cracks and potholes in spring.

Pre-season catch basin checklist for property managers

Use this in October, before the heavy rain days stack up.

• Walk the site and map every catch basin, trench drain and area drain. Number them on a site plan.
• Lift a few grates and look into the sump. If sediment is more than about halfway up, it needs cleaning.
• Clear leaves and litter off every grate with a long-handled rake or broom, never by hand.
• Note any basin that ponded last winter. Those are first on the list.
• Check for broken or shifted grates and frames. Flag them as trip hazards.
• Look for oil sheen in sumps near loading docks, fuel areas or parking for fleet vehicles.
• Ask your landscaper to bag leaves, not blow them onto pavement.
• Book cleaning before the first big rain, then schedule a follow-up check once the trees are bare.
• Keep dated records and photos of inspections and cleanings for your files, your strata council and your insurer.
• Do not send staff into catch basins, manholes or interceptor chambers. Larger underground chambers can meet the definition of a confined space under WorkSafeBC's regulation, which requires a written entry program, trained workers and permits.

10 years of Vancouver rainfall

The full table is below. Use it to show your strata council or owners how much of the year's rain lands in the fall and early winter.

Book a free catch basin inspection

We'll walk your site, check every basin, and tell you which ones need cleaning before the heavy rain arrives. You get a written quote, with no obligation to book.

We clean catch basins with hydrovac trucks for strata and commercial properties across Metro Vancouver, including Vancouver, Surrey, Burnaby and Richmond, from our office in Port Coquitlam. See our hydrovac services.

Book my free catch basin inspection or call 604.220.9475.

10-year rainfall history: Vancouver International Airport

Vancouver averaged 1,140.8 mm of precipitation a year from 2016 to 2025, and October to December alone averaged 488 mm, about 43% of the year.

Source: ECCC historical climate data, station Vancouver Intl A (Climate ID 1108395), pulled October 21, 2026 through the MSC GeoMet API. Normals are from Vancouver Int'l A (Climate ID 1108447). A few months are missing one to three days of readings.

Frequently asked questions

Will winter 2026-27 be rainier than normal in Vancouver?

The current outlooks don't point that way. ECCC's seasonal forecast from September 30, 2026 shows no strong wet or dry signal for the Lower Mainland from November to January, and a strong El Niño usually tilts the BC coast warmer and often drier. Expect a mild winter with more rain than snow, and still plan for the usual heavy rain days.

Does El Niño bring more rain to Vancouver?

No. In BC, El Niño winters tend to be warmer and are often drier, according to ECCC. Mild temperatures do mean more of the winter's precipitation falls as rain instead of snow, and big storms still happen: the wettest day at Vancouver's airport since 1950, 89.4 mm on Christmas Day 1972, came during a strong El Niño winter.

When is atmospheric river season in Metro Vancouver?

Atmospheric rivers can arrive any time, but heavy rain days cluster in fall and early winter. At Vancouver International Airport, 49 of the 67 days with 25 mm or more of rain from 2016 to 2025 fell between October and January.

When should I clean the catch basins on my property?

Book a cleaning before leaf drop and the first heavy rain, usually in October, then check the grates again once the trees are bare. The City of Vancouver recommends checking catch basins before and after heavy rain and when trees have shed their leaves.

Who is responsible for catch basins on a strata or commercial property?

On a strata, catch basins in shared parking areas are often common property, which the strata corporation must repair and maintain under section 72 of the Strata Property Act. Check your city's drainage bylaw for any extra rules.

Can a blocked catch basin create a slip and fall risk?

Yes. Water that ponds beside a plugged drain can freeze on cold nights, and Vancouver averages about 10 nights at or below 0 C in January. BC's Occupiers Liability Act requires occupiers to take reasonable care to keep people reasonably safe, so keeping drains working is part of winter risk management.