City Temperature Comparison - Dashboard

Today we are going to take a look at a dashboard that lets us compare the temperatures from different weather stations in a bunch of different ways.

We will begin, as always, with Edmonton vs. Calgary.

Edmonton & Calgary: 30-Year Average Temperatures

Here we have the average daily temperatures for Edmonton and Calgary. For complicated reasons this chart unfortunately doesn't have a legend, but Edmonton is the darker blue, and Calgary is lighter. The top half shows the High temperatures, and the bottom half has the Lows. The linecharts are the temperatures themselves, and the barcharts are the differences between the two cities. And if you hover over the dashboard it will give the numbers for the various days.

We will talk about this more in detail in a bit, but in general we can see:

• Edmonton's average Highs during the winter are quite a bit cooler than Calgary's - the difference is about 4°C or 5°C for December & January.
• Edmonton's average Lows during the winter are only a bit cooler than Calgary's - the difference in January is about 2°C.
• Edmonton's average Highs for May & June are maybe a degree or two warmer than Calgary's .
• Edmonton's average Lows for May-September are about 2°C warmer than Calgary's.

The biggest differences are during the winter, and so I think it will be easiest if we flip this chart from January-December to a more winter-centric July-June:


Edmonton & Calgary: Winter-centric Version

Here we have the same data that we were just looking at, but this time it runs from July-June so that the winter falls in the middle of the chart.

And for the Highs we can see that Edmonton and Calgary are pretty close for most of the year, but things start to diverge around November and then join back up around April. The big difference in the average Highs peaks in mid-January, with Calgary's average at around 0°C and Edmonton's at -7°C.

For the Lows during the summer Edmonton is usually a few degrees warmer, but then as we move into winter that flips and Calgary is a bit warmer. That also peaks around mid-January, with Calgary at -13°C and Edmonton a few degrees cooler at -16°C, but the difference is much less than with the Highs.

Edmonton & Winnipeg

And as usual, after looking at Calgary here we've moved on to Winnipeg.

For the average Highs during the summer Winnipeg is 3°C or 4°C warmer than Edmonton. But in the winter that flips, and in January & February Edmonton's average Highs are 5°C to 7°C warmer than Winnipeg's. If you switch the dropdown in this dashboard to Calgary, their average Highs in January are 10°C to 12°C warmer than Winnipeg. Calgary's average Highs bottom out at about -4°C, for Edmonton it's -8°C, and for Winnipeg it's -13°C.

For the average Lows Edmonton and Winnipeg are fairly similar during the summer, but then in the winter Edmonton's Lows are 8°C to 10°C warmer, and Calgary's are 10°C to 12°C warmer. Calgary's average Lows bottom out at about -16°C, for Edmonton it's -17°C, and for Winnipeg it's -23°C.

Edmonton & Montréal

These dashboards have the data for 9 Canadian cities, and we won't go through all of them here, but we will do one more example with Montréal. Not surprisingly, on-average Montréal is warmer than Edmonton for most of the year. But what might be surprising is how close the average temperatures are in January-March.

For the Highs the biggest gap is in November & December, with Montréal about 7°C warmer than Edmonton's cool falls. For February, March & April that difference basically disappears though - Edmonton gets colder days than Montréal, but also more warm ones. And in the summer Montréal's average Highs are about 3°C warmer than Edmonton's.

For the Lows things are similar, with Montréal about 7°C warmer than Edmonton in November & December, about the same in January & February, and then about 4°C warmer for most of the year.

Here's a look at Edmonton, Calgary & Winnipeg all compared against Montréal. In January & February Calgary's average winter Highs are actually about 4°C warmer than Montréal's. And Montréal is pretty consistently warmer than Winnipeg, although the summer Highs are similar.

Edmonton & Calgary: 2019

Everything that we have looked at so far today has been 30-year averages, but this dashboard can also be used to compare a single year. Here we have the temperatures for 2019 for Edmonton & Calgary.

The daily temperatures for the two cities follow each other very closely - the extremely cold February 2019 shows up in the Highs & the Lows for both Edmonton & Calgary.

The largest gap 18.7°C on January 10th with Calgary's High up at 9.8°C while Edmonton's was down at -8.9°C. The largest gap for Edmonton was 12°C on May 21st, with Edmonton at 19.6°C and Calgary at 7.6°C, and that was part of an entire cool week for Calgary.


Edmonton History

One other thing that we can use this dashboard for is to compare Edmonton's current temperatures to its past. Here we have the 20-year average for 2000-2019 compared to 1880-1899

Unfortunately because of the way this is set up both eras appear in blue, but in the bargraph a value that is above 0 means that 2000-2019 is warmer, and below 0 means 1880-1899 was warmer.

For the Lows we can see that modern temperatures are warmer than they used to be for almost the entire year (with a weird little exception right around December 8th). Typically modern Lows are about 4°C warmer than they used to be, but in January & February that increases to 8°C to 10°C.

For the Highs January & February have also seen the biggest changes, warming by about 6°C. For the rest of the year the Highs are a little more variable. For the summer months of July, August & September the modern average temperatures are a little bit warmer, but generally by less than 1°C.

For some context here we have 2000-2019 vs. 1880-1899 for Edmonton, Calgary, Winnipeg and Montréal. It's easiest to focus on the bargraphs, and the patterns for Edmonton, Calgary & Winnipeg are all quite similar, with lots of warming in the winter, and a year-round increase in Low temperatures. Montréal is a bit different though, also seeing an increase in late-summer High temperatures.

This chart is the same idea, but it cycles through all of the years since 1880 for Edmonton. Watching all of the years roll by the big changes really start to happen in 1980-1999, and then 2000-2019.


Blatchford & The Edmonton International: 2019

One final thing that we can do with this dashboard is compare the temperatures of downtown Edmonton (Blatchford) to the International Airport.

For the average High temperatures the two stations are fairly close for most of the year, with the biggest gap happening in the spring with Blatchford about 1.5°C warmer than the International. For the average Lows the International is about 3.5°C colder than Blatchford for most of the year.

Those are just the averages though, so let's look at one specific year:

Daily data is a little bumpy, and so here it's easiest to focus on the bargraphs. For the Highs we see a lot of spikes in March with Blatchford 5°C or 8°C warmer than the International.

For the Lows, for some of the very cold days in February there was a 10°C or 12°C difference between the stations: on February 4th Blatchford hit -29.5°C while the International was at -39.5°C; on March 2nd Blatchford was at -28°C with the International at -36.9°C, and on March 6th Blatchford hit -19.1°C with the International at -29.2°C.

You might think that Blatchford is warmer just because it's the big city, but we can compare the airport to a few other outlying stations:

Blatchford tends to be the warmest station in the region, but Stony Plain's winter Lows also average about 4°C warmer than the International. For Namao and Ft. Saskatchewan the differences are not as big, but they're also both consistently warmer than the airport. We have talked about this before, but when the airport gets cold it gets really cold.

And that brings us to the end for today. All of these examples were Edmonton-centric, but the data is also available for Vancouver, Calgary, Winnipeg, Toronto, Ottawa, Montréal & St. John's.

November 2019 Review / December 2019 Preview

November 2019 - was it warm or cold? Snowy or not snowy? Let's take a look.

High Temperatures

The High temperatures for November 2019 started off around average, then dropped for a week, then spent 11 days-in-a-row above average, and then finally cooled over for the last week.

The grey band in this chart shows the 25th-75th percentiles, where the Highs will fall about half of the time. And we did have a few days outside of that, but we didn't come close to the warmest or coldest temperatures for the last 30 years (the orange and blue areas) or to the warmest and coldest since 1880 (the orange and blue lines).

Looking at the individual numbers we had 10 days with Highs of 0°C or colder, and 20 days with Highs above freezing. We average 18.6 days above freezing in November, so 2019 was just a little bit less frozen than normal. We didn't have any Highs above 15°C, but we did have two above 10°C with the 17th at 11.9°C and the 23rd at 10.6°C.

Our coldest High was -12.1°C on the 10th. The last time that November had a High below -15°C was 2014, which had one High all the way down at -20.4°C.

The average High of 1.3°C was the 11th warmest out of the past 20 years.


Low Temperatures

For the low temperatures we were right down at the bottom of the 30-year range early in the month, with the 7th at -13.6°C, and the 11th at 19.6°C. And then the 23rd, 24th & 25th were right at the top of the 30-year range.

We didn't have any -20°C Lows this November, although we came really close with -19.6°C on the 11th. We also had 4 Lows above freezing, and November's average is 3.4 days.

November can sometimes have some really cold days, and those show up here as the dark blue boxes. 2014, 2011, 2010, 2006 & 2003 all had November days below -25°C.

The average Low of -7°C was the 11th warmest out of the past 20 years.


2019 So Far

When we add up all of the High & Low temperatures for 2019 so far it has been 0.2°C warmer than the 20th century average. There's still a month left, but right now it's about the 65th warmest out of 139 years going back to 1880.

The bargraph at the bottom shows how things have gone so far in 2019: warm January, really cold February (Edmonton's 5th coldest), slightly warm March, pretty average summer, warmish September, coolish October, and finally a warmish November. All of that talk of "warm" or "cold" is relative to the 20th century though, and not necessarily to recent years.

Here we have the history of the monthly mean temperatures for the last 20 years, with each month represented as a bubble.

For 2019 the giant blue bubble for the cold February stands out. And the very average summer was quite different from the past few years. Once we hit fall all of the years get a little bit more random, and alternating warmish/coldish/warmish months aren't unusual.

Looking ahead to December, in the past 5 years we have had 4 warmer than average final months. But then for 2007-2013 6-of-7 Decembers were colder than average.


Precipitation

For total precipitation (rain + snow) November 2019 was just a bit above average at both Blatchford and the International. The November average is 20.5mm, and the International recorded 23.7mm with Blatchford at 24.8mm.

It's worth mentioning that some of that precipitation (4.1mm at the International) fell as rain. November 2019 had 4 rainy days, which was down from the 6 in 2018, and a bit below the average of 4.5 days.

For the year so far Blatchford has recorded 454 mm of total precipitation which is just above average, while the International was a little below at 412m.

That's a change from 2017 & 2018 where Blatchford's precipitation had been more than 100mm below the International.

For a bit of context, in this (messy) chart we have the January-November 2019 precipitation for 8 other Canadian cities compared to Edmonton. Edmonton is the blue line down with Calgary, Winnipeg & Regina all around 400-500mm. Toronto, Ottawa & Vancouver are all over 800mm and roughly double the prairie cities. And then Montréal and St. John's are up around 1,200mm.


Snow

November might have felt a bit snowy, or maybe not? With 21.2cm at the airport it was just a bit above November's average of 20.1cm, but it was snowier than our below-average October and September.

Do you know who hasn't had below-average snow?

Calgary just had it's snowiest November since 1966 with 43.4cm (narrowly passing 2014's 43.2cm). That combined with an above-average October and a snowiest-since-1972 September brings Calgary's total for September-November to 93.6cm. That is their snowiest fall since 1925's 131.9cm, and their 3rd snowiest on record.

Here's another messy chart to show Calgary's cumulative snow compared to everyone else. Their 93.9cm is more than double Winnipeg's 43.2cm 2nd place, and then the rest of the cities are down around 30cm or less.


Snowdepth

Here we have the snowdepth at Blatchford and the International. At the end of November Blatchford is down near 1cm, while the International is a bit above the average with 17cm. Both of those numbers will likely grow as we move through winter towards the big melt in March.

Winter 2019-2020 is just getting started, and this chart shows that we normally have measurable snow on the ground from around now until about the end of March.


December Temperatures

For December Temperatures on average we have about 10 days with Highs above 0°C. Some years have more than 15: 2017, 2011, 2006, 2005, 2004, 2003, 2002 & 1999. And then others have 6 days or less: 2012, 2010, 2009, 2008, 2007, 2001, 2000. Last year December 2018 was pretty average with 9 above-freezing days.

For the Lows, in the last 20 years there have been 2 Decembers which didn't hit -20°C, and 11 which didn't hit -25°C. We are definitely entering the season of weeklong deepfreezes, but luckily they usually get balanced with a mild week or two.