2018 in Review - Part 1 - Temperatures

Today is Part 1 of the 2018 Edmonton Weather Nerdery Year-in-Review, and we will be looking at the year's temperatures.

• In Part 2 will we will look at 2018's overall precipitation.
• In Part 3 will we will focus on 2018's snow.

The charts today are all ones that have been used in the past, and since some of these can be complicated there will be links back to the original posts that have the full explanations.

High Temperatures

Here we have the High temperatures for the year.

The colourful stuff in the background of this chart is the range of temperatures that have been recorded at Environment Canada's Blatchford weather station since 1996. The average High for each day is the white line in the centre; it is surrounded by a grey band for the 25th-75th percentiles (where temperatures will fall roughly half of the time); and outside of that are the warmest temperatures since 1996 in orange and the coldest in blue. And finally, the all-time warmest and coldest temperatures going back to 1880 are shown as the faint lines that are furthest from the average.

In 2018 we set two records for warmest-since-1880 Highs: on August 9 & October 17. We also set three records for coldest-since-1880 Highs: on April 5, August 12 & September 13. Those new records are circled in red in the chart. Breaking records always sounds really impressive, but it usually happens a few times a year and we looked at that earlier in detail in How Often Does Edmonton Break Temperature Records? and in Record Watch: October 17, 2018.

In addition to the since-1880 records, the orange dots in this chart also show the days this year which were the warmest-since-1996. There were 22 more of those, mostly in May, June & July. And there were 18 more coldest-since-1996 Highs which are shown in blue, and a lot of those were in April & September.

The Red & Blue highlighting in this chart shows days that were above or below average. With that we can see the many swings from coldsnap-to-heatwave (or visa versa) that happened throughout the year. February, April & September were all really cold, while January, May, November & December were all quite warm. We will look at the months in more detail later on.


Low Temperatures

And here we have the Low temperatures for 2018.

We set three records for warmest-since-1880 Lows: on May 8, May 24 & June 25. There were also 15 more warmest-since-1996 Lows, again mostly in May, June & July.

We didn't set any coldest-since-1880 Lows, but those don't happen very often. We did have 22 coldest-since-1996 Lows spread throughout the year, and a lot of those were in April & September.


Warm & Cold Months

In this chart we break things down further, and we can see how much warmer/colder each month of the year was compared to the 20th century average. And the recent 5-Year average is also shown as the grey, dotted line. The full explanation of this chart was in How Warm is 2017 - the Months.

For 2018 we had 5 months which were colder than the 20th century average for that month: February, March, April, September and October. And there were 7 months which were warmer: January, May, June, July, August, November and December.

Notably:

• May was the #1 warmest May going back to 1880.
• June was our 6th warmest June.
• September was our 5th coldest September.

We have just finished a December which was relatively pleasant at 4°C warmer than the 20th century average, but that was only enough to rank as 33rd warmest. January was also 4.2°C above the 20th century average, which put it as 37th warmest. And February was the 47th coldest at about -2°C below the 20th century average, but it was well below the recent average and was 4-6°C colder than most of the recent Februarys in the chart.

Our cold April and hot May meant that 2018 jumped straight from winter into summer. And then the very cold September put an abrupt end to summer, plunging us into what felt like the middle of fall.

Here's another look at how warm & cold months have been distributed throughout the last 20 years.

Almost every year here had more warm months than cold ones. 2002 is the only year with a 6-6 warm/cold split. This year we had 7-5 warm/cold, which also happened in 2000, 2004, 2009 & 2013. Last year in 2017 there were only 3 months colder than the 20th century average, 2016 had 2, and 2015 was a big El Niño year with all months warmer than the 20th century average.

Right now this chart is mostly full of orange bubbles, but that has changed over the years:

This chart shows how warm & cold months have been distributed since 1880. The "20-Year Average Difference" on the right shows the average temperature for each month has changed over time. We took a detailed look at that in The Months through the Years.


The Horserace

We've looked at the days and at the months, but how does 2018 compare to other recent years?

For a full explanation of this chart it's easiest to refer back to the original discussion of it in How warm is 2016? (September Edition). Generally though, it tracks how much warmer each day of the year was compared to the 20th century average - warm days get points and cold days lose them. The blue and orange background is the range of all the years going back to 1880, and they are grouped together like that because showing each individual year gets too messy. To keep things simple the last 10 years are shown here as a reference.

Every year follows a different path, and 2018 started off promisingly enough with a warm~ish January. But then it dropped during the cold February. Then it really dropped during April, and was down below the 20th century average for a bit. But then the really warm May and June pushed it back to the positive side. Then the cold, early fall pushed it down again in September and October. And to end off the year it climbed up again pretty steadily during the relatively mild November and December.

And with that 2018 ends up as Edmonton's 34th warmest year since 1880, which is a bit on the cooler-side of recent years. It's nowhere near the really warm El Niño years like #3 2016 and #4 2015. It's also not as cold as the cooler years like #71 2009 and #47 2014. But of the "typical" recent years - from #16 2017 down to #40 2013 - 2018 was closer to the low end. It was also essentially tied with #36 2011, averaging just 0.003°C warmer across the whole year.


Warmest and Coldest Years

This chart lets us compare all of Edmonton's warmest & coldest years, going back to 1880.

The explanation for this chart is in Edmonton's Warmest Years, but it essentially averages all the temperatures for an entire year, and then compares that to the average for the 20th century. The National Oceanic and Atmospheric Administration use the 20th century average as their baseline, and that is why we are using it here.

2018 is the 34th warmest, at 0.8°C warmer than the 20th century average. That's down from 2017 which was 1.6°C warmer, and way down from the El Niño years 2015 & 2016 which were up at 2.5°C and 2.9°C respectively.

This chart also shows the 5-year average, which really shot up in the mid-1970s and has stayed high ever since. Right now that 5-year average is at 1.7°C above the 20th century average, and that is the highest that it has ever been, even though 2018 was a bit cool~ish. That 1.7°C just edges-out the previous high of 1.65°C from 1990.


Calgary, Winnipeg & Montréal

For a bit more context, here we have the warmest & coldest years for Calgary, Winnipeg & Montréal. How was 2018 in those cities?

• in Calgary it was cool~ish, coming in as 40th warmest and 0.5°C above the 20th century average.
• in Winnipeg it was cold, as 57th warmest and only 0.1°C warmer than the 20th century.
• in Montréal it was warm, as 18th warmest and 1°C warmer than the 20th century.

Right now Edmonton's 5-year average temperature is at 1.7°C above the 20th century average. For Calgary it's at about 1.4°C, for Winnipeg it's only at about 0.7°C, and for Montréal it's at about 1.1°C. Since 2000 Edmonton, Calgary and Montréal haven't had any below-average years, but Winnipeg has had 5, and that's why its average is relatively low.

Here are the individual charts if you want to take a closer look:

If we watch the 5-year averages we can see that all of the cities follow a similar pattern, with lots of cold years a century ago, and lots of warm years since the mid-1980s. We also see that certain years - 1931, 1981, 1987, 2016 - were warm at several stations, while a year like 1996 was cold for all of the weather stations.

Whenever we use the data for these other cities I ike to warn that what we're looking at is not necessarily 100% equivalent: the Blatchford weather station for Edmonton is downtown~ish; Calgary's is on the edge of the city; Winnipeg's is on the edge of the city~ish; and Montréal's is the furthest from downtown, but it is surrounded by city, and it is near the St. Lawrence. And so this isn't going to be a true apples-to-apples comparison, but it is what we have available.

Outlying Areas

You might think "Edmonton, Calgary, Winnipeg and Montréal are all big cities, so of course they've warmed up." And that is an excellent point, and so this chart tries to do the same comparison with the data that is available for 3 rural stations which are near Edmonton: Calmar, Campsie & Sion. We have used these stations before in:

• Rural Alberta & the Heat Island Effect
• Climate Hardiness Zones
• Frost-Free Days: Part 2
• Edmonton's Warmest & Coldest Summers

These stations all have roughly a century of continuous data, so they are good for making comparisons. Unfortunately they aren't perfect, because the measurements didn't start until the mid-1910's and they all ended in the mid-2000s. So this chart has the warmest & coldest years for those stations based on the limited data available.

One of the slides of this animation also combines data from the Calmar station (1916-1960) with the Edmonton International Airport (1961-2018) to try to get a longer-term comparison. The two stations are located fairly close to one another at about 15km apart, but the International averages about 0.6°C colder than Calmar. 0.6°C doesn't sound like a lot, but it's enough to noticeably shift the warm/cold years in this chart. So the Calmar & EIA slide is included here as an experiment, but it doesn't actually work very well.

With this admittedly imperfect chart we see a similar pattern to what we saw for Edmonton, Calgary, Winnipeg and Montréal, with lots of cold years a century ago and lots of warm years from the mid-1980s onwards. And when the measurements for these stations stopped in the mid-2000s all 3 of them were averaging 1~1.5°C warmer than their 20th century averages.

And so this definitely is not a perfect comparison. But the rural stations have seen similar increases to what we have seen in the big cities, and so the cities are not warming up just because they are cities.


Really Cold Days

Switching back to the data for Edmonton alone again, here we are looking at the really cold days each winter. In 2018 Blatchford had:

• 24 days with Low temperatures of -20°C or below
• 5 days at -25°C or below
• 1 day at -30°C or below (that was February 4th at -30.7°C)

Since 1880 the number of cold days each year has been in a fairly steady decline, although the numbers bounce around on a year-to-year basis. 2015 & 2016 were both El Niño years and had very few cold days. But just before that 2008-2014 had quite a few years with a lot of cold days.

2018's results were right around the average.


Really Hot Days

Right now summer feels like it was a long time ago, but we really did have a hot (though short) one this year.

We had 55 days which hit 25°C. That was the 5th highest since 1880, after 1922 with 57, 1894 with 59, 1961 with 60, and 1898 in top spot with 64. And this year we had a ridiculously cold September and a cold end to August, so all of those hot days fit into May through mid-August.

In recent years 2017 was in 9th place with 50 25°C days, and 2015 was 6th with 52. But even about 5 years ago things were way down, with 21 days in 2011, 20 in 2010 and 19 in 2005. Since 1880 there has obviously been a lot of year-to-year variability, but the 5-year average has mostly been between about 30 and 40 days. Recently though 2014-2018 have all been above 40 days, and so our 5-Year average is 47.6 25°C days.

For really hot days 2018 was also on the high side of things, with 19 days hitting 28°C, 7 at 30°C and 2 at 32°C. Historically there's been a lot of variability in those days as well, and the last 5 years were fairly hot, but not exceptional. We looked at all of that in a more detail in Edmonton's Warmest & Coldest Summers.

And that's it for the 2018 in Review - Part 1 - Temperatures. Later in the week we'll be back with Part 2 - Precipitation.

And if you are wondering what previous years-in-review looked like:

• 2017 in Review - Temperatures
• 2016 in Review - Temperatures