In the past I've done comparisons to a few other locations because I find it useful to give some context to Edmonton's numbers. Today's format will be similar: we'll look at yearly temperatures; break those down into summer and winter; and then look at precipitation. For reference, here are the previous comparisons:
As usual I'm using data from Environment Canada because it's easy to download a long, reliable history. For Montreal I'll be using the weather station at Pierre Elliot Trudeau airport which is about 13km from downtown, compared to Edmonton Blatchford which is about 4km from downtown. Montreal had a nice central weather station located right downtown at McGill with readings going all the way back to 1871, but those stop in 1993 so they aren't any help today.
As I've done for the previous comparisons, here I'll be taking my standard rollercoaster chart that shows how Edmonton's temperature varies throughout the year, and overlaying the Montreal data on top of it.
Daily Highs
In the background here we have Edmonton's recent history of high temperatures for each day of the year. This a chart that I use all of the time, but it could use some explanation:
- The white line in the centre is the average temperature based on all of the years from 1995 through 2016.
- Surrounding that average is a grey band for the 25-75th percentiles, which is where temperatures will fall roughly half of the time.
- Finally, the oranges and blues are the warm and cold extremes recorded between 1995 and 2016.
And for almost the entire year Montreal's average high temperature is several degrees above Edmonton's, but there is a stretch from February through May where they are pretty close. Notably though, October and especially November are much warmer in Montreal than in Edmonton.
Daily Lows
Here we have the daily lows for the year, and again Montreal is well above Edmonton - except for a little window in February and March.
Now lets take a closer look at Summer and Winter, and we'll add in Calgary and Winnipeg for comparison.
Summer Highs
So here we are zoomed in on the daily high temperatures for the summer months. Calgary has been added in red, Winnipeg in green, and Montreal is still in purple.
Winnipeg and Montreal are very close, averaging 3°C to 4°C hotter than the Alberta cities.
One thing I should mention here is humidity - I don't normally talk about it, because I'm from Alberta where humidity is basically a foreign concept. It's certainly not foreign to central Canada though, and the high drybulb temperature that we see for Montreal would undoubtedly be combined with much higher relative humidity than Edmonton or Calgary would ever experience. Environment Canada doesn't include RH in their daily data so I don't have any numbers to compare, but it's just worth pointing that out.
Summer Lows
For the summer lows things shift a bit. Montreal stays about 3°C to 4°C warmer at night than Edmonton and Winnipeg, and Calgary is another 3°C lower than that. The very lowest-lows that Montreal has recorded since 1995 are a little bit above Calgary's average lows, and just a bit below the Edmonton average.
Winter Highs
Things get interesting in winter.
There is a lot going on here, but just looking at Edmonton's average in white and Montreal's in purple, for all of November Montreal averages about 5°C warmer than Edmonton. That gap closes a bit through December. And then starting around mid-January the average high temperatures for the two cities are about the same, and that continues through spring.
While the average high temperatures are close, looking at the coldest days Montreal has recorded since 1995, the highs rarely drop below -20°C while Edmonton has had -25°C and even two daytime highs below -30°C.
For Calgary, in January and February the average high is actually about 4°C warmer than Montreal's or Edmonton's. And Winnipeg is Winnipeg.
Winter Lows
And here are the winter lows.
For all of November the average lows for Montreal are about 5°C warmer than Edmonton, Calgary and Winnipeg. But in December Edmonton and Calgary level off, while Montreal and Winnipeg keep dropping. So by mid-January, the lows for Montreal, Edmonton and Calgary have all synced up, and they stay that way until spring (and again, Winnipeg is off doing its own thing).
But again those are just the averages. Looking at Montreal's very coldest days, since 1995 there haven't been any lows below -30°C, while Edmonton (and Calgary too) have had a few extreme prairie nights below -35°C.
What's interesting here is the distinction between November/December and January/February. In the depths of winter in January/February the average highs & lows for Edmonton and Montreal are a lot alike. The big difference is that Edmonton gets an extra month-and-a-half of that, because things start so much earlier in November/December.
Precipitation
Finally for today, we'll look at precipitation.
This is Edmonton's yearly breakdown of precipitation, with the Montreal average and recent maximum overlaid on top.
Edmonton's precipitation has a really noticeable peak in July, but that's not the case for Montreal at all. Montreal is very consistent, and most months are at about the same level as the Edmonton peak in July. Montreal's lowest month is February averaging 58mm, and it's highest is December at 98mm. In comparison, Edmonton ranges from 17mm in February to 88mm in July.
And for Montreal's maximum months, outside of June and July all of the others tend to double or triple the Edmonton maximum,
For further comparison, here are the averages for Calgary and Winnipeg added as well:
This is a little messy, but we can see how similar the precipitation distribution is for the three prairie cities - a peak in the summer months and significant drop in the winter - especially when compared to Montreal.
Over the course of a year, here is how all of that precipitation adds up:
Edmonton averages about 425mm of precipitation per year, and the highest recent year was 1996 with 650mm. Montreal completely blows that away, averaging 1025mm per year, and the recent maximum was 1350mm in 2006.
That is just overall precipitation, and we haven't specifically looked at snow yet. Snow is part of the reason that I wanted to look at Montreal in the first place though, and we'll come back to that in the next few weeks.
So for now, I think this is the last of the city-comparisons that I will do. I've got Calgary to show how things can vary within the province, Winnipeg as a representative of a second prairie province, and Montreal is a good stand-in for central Canada.
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