Why has Pitt Meadows broken so many weather records?

The City of Pitt Meadows refers to itself as ‘The Natural Place’ — but at times over the past six months, the weather has been far from normal. 

Besides setting all-time heat records in September and July, the city also set at least three separate rainfall records.

The rainfall records, which occurred once in August and twice in April, come as the city develops its climate action strategy, a plan that pledges to prepare the community for impacts associated with climate change and reduce greenhouse gas emissions. 

But following 15 straight months of record-high global temperatures, and a summer that was officially the hottest on record in the northern hemisphere, the city may face some additional burdens associated with climate change that other municipalities may not. 

In a year with little precipitation in the spring, dry soil conditions could raise the temperature of heat waves, said Lualwai Admasu, a PhD student studying atmospheric sciences at the University of British Columbia.

It’s a crucial factor considering that 78 per cent of Pitt Meadows is composed of agricultural land. 

“When you have water in the ground, think of it as sweating,” Admasu said. “Warm air can evaporate the water before warming up the ground. If it’s the other way around, you have very dry soil, it’s going to directly heat it up.” 

However, a high volume of rain in April — like the city had this spring — could reduce the risk of extended heat waves later in the summer. 

Pitt Meadows received over 333 millimetres of rain this April, the highest volume of precipitation in the month in the last four years, according to an online weather dashboard that collects data from Environment and Climate Change Canada.  

It’s difficult to explain a reason for the three rainfall records in five months without thorough analysis of the individual storms, Admasu said. 

There are many variabilities in the weather modelling system. 

Although climate change is warming the planet at a fast rate, annual temperatures in a city or region still may fluctuate annually due to larger climatic events or microclimates caused by natural factors, such as a city’s proximity to a mountain range or the ocean. 

“We have climate change, slowly but surely we’re increasing our temperatures, but within that time scale is what we call inter annual variability,” Admasu said. “You can have large variabilities.” 

El Niño and La Niña events, climate events that occur in the Pacific region that warm and cool temperatures respectively, are one key driver for those oscillations. 

An El Niño year, which causes the Pacific Ocean to heat up more than normal, likely leads to drier and hotter weather conditions. The latest El Niño phenomenon began in roughly June 2023 — peaking in December — before beginning to taper off, likely paving the way for La Niña conditions this year. 

A higher emphasis on collecting data and enhancing weather measurement tools may also be one explanation for the recent string of weather records in Pitt Meadows. 

“If you have everything that’s impacting Pitt Meadows, with good observational data, you can train your model to make [forecasts] closer,” said Admasu, adding that data collection is especially important to understand how a region is impacted by a warming planet.

“Getting as much weather data as possible is primary when it comes to weather forecasts.” 

The microclimate in Pitt Meadows is classified as “moderate temperate humid,” Admasu said. The climate is not too dissimilar from other regions in the Lower Mainland, with wet seasons stretching from roughly November to April and relatively shorter summers.  

Pitt Meadows’ ongoing climate action strategy is slated to address impacts related to buildings, infrastructure and emergency management, among various other areas. Residents were permitted to give feedback on the plan in the summer, and open houses were held in August and September. 

Staff are currently reviewing the feedback and are going to report back to council at a later date. The next council meeting is scheduled for Oct. 8. 

Down the road, Admasu said that cities like Pitt Meadows need to prioritize both mitigation and adaptation in their climate action plans. Simple strategies like education and heightening awareness could go a long way in alerting residents to extreme events. 

Improving long-term forecasts would also give a municipality a better chance at preparing for extreme weather. 

Although it may seem like two week forecasts are enough to give a warning to residents, it’s not enough time to plan, gather volunteers and decide where to place them to combat climatic events that have become more common in recent years. 

“B.C. is affected by heat waves, floods, wildfires, we know these things,” Admasu said. “The more you know these things, you can also prepare certain infrastructure.”