Bixi Montréal was the first major bike share in North America when it opened in 2009. The technology was sold and the familiar Bixi bikes can now be seen in Toronto, New York, Chicago, Boston, Washington, D.C., London, and many other cities around the world. Bixi’s open data contains information on all trips since 2014 that last longer than 1 minute and shorter than 2 hours, including start/end times and docking stations. There’s a lot to analyze. In particular, I’m interested in how the weather dictates the usage of Bixi. In addition, the City of Montreal has about 20 bicycle counters set up along various bike routes in the city. While this data is a bit less reliable than Bixi’s (several counters have had outages that are not always easy to detect in the data), it’s useful in that Bixi only operates from April 15-November 15. Bike counter data will allow us to see how cyclists react when temperatures drop during the winter.
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After a particularly hot and humid summer, temperatures have finally cooled off in Montréal. Weather models have started showing light snow approaching the area in the next couple of weeks, and it looks like our first 0°C temperatures could arrive in the next few days. So, when do we typically start seeing this wintry weather in Montréal?
To answer this, I’ve looked at Environment and Climate Change Canada data for Montréal’s Trudeau airport (CYUL), which has observations since 1942. We’ll focus on two components of wintry weather – cold temperatures and snow.
First “freezing” temperatures
First, let’s look at the first autumn day on which the minimum daily temperature reaches at least 0°C. In the plot below, the date for each year is plotted, with a 10-year centered running average shown in the blue line. Prior to around 1990, the first 0°C day almost always occurred between the last week of September and the third week of October. Since 2005, however, the first 0°C day has always occurred between the second week of October and the first week of November. The 10-year average first 0°C day is now October 25, an increase of more than 2 weeks since 1990, when the 10-year average was around October 8.