How Warm is 2017 - the Months

A few weeks ago we looked at how 2017's temperatures compared to other years, in How Warm is 2017? (October Edition). And ultimately we ended up with this:

Comparison of 2007 through 2017

So far 2017 has been fairly warm compared to other recent years, coming in behind 2012, 2015 and 2016, but above all of the rest.

Today we're going to break that down further to see how the individual months compare. This is mostly just an excuse to try out a new chart, so here we go:

Warm and Cold Months

This chart looks at how warm each month of each year was, compared to the average for that month during the 20th century. This uses the mean daily temperature again, rather than the highs or the lows

It rushes through all of the years pretty quickly, but I hope it gives a sense of how things bounce around. Most years have some warm months and some cold months, and that was even true 130 years ago. The balance of warm vs. cold has changed over time though, and with the dotted grey line we can see how the 5-year average moves around.

In a few weeks I'll do a separate post which takes a closer look at some of the more interesting years from this chart. For today though, we're going to stick with recent history.


Here's the chart for 2017, so far. The bars shows how many degrees we were above or below the 20th century average, and the dotted grey line shows the 5-Year average.

Looking at January, this year our mean daily temperature averaged -8.1°C, which is 5.4°C above the 20th century average of -13.5°C. And at the other end, in September our average temperature of 15.6°C was 4.8°C above the 20th century average of 10.8°C. Most of the other months were a couple of degrees warmer than the 20th century, except for the slightly cool March and April.

Looking at the 5-Year average, most months in 2017 have matched it fairly closely. The two biggest gaps were March which was almost 2°C below the recent average, and September at almost 3°C above.


Here is 2016 as another quick comparison. We can see how consistently warm it was from January through September, before temperatures took a nosedive in October, and then shot up again in November.


To get a bit more of a sense of recent history, this chart cycles through 2010-2017.

Most of the years here have a mix of warmer-than-typical and colder-than-typical months. 2012 had a cold October-December, followed by a warm January-February 2013. 2014 had a warm January, but then a cold February through May. 2015 was notable for having all 12 months on the positive side of the 20th century average.

5 Year Average

One final, new chart today, which focuses on how the 5-year average changes over time.

In previous posts we've looked at the fact that Edmonton's temperatures in the winter are more variable than in the summer, and we see that again here. If you watch the 5-year average line for summer months you'll see that the line is very constant. From 1880-2017 it stays in a narrow band within +/- 2°C of the 20th century average. Right now that average is at the very top of its range, following a series of relatively warm summers.

The average for the winter months fluctuates much more, with a range of +/-8°C. For January and February our recent average is again near the top of the range, but for November and December we've actually stayed pretty close to the 20th century average.

And that's it for today. At the end of every month I find myself saying "April was cold" or "September was fairly warm." The charts today let us actually compare each month to recent years, and to longer-term history.

When talking about monthly average temperatures we lose track of the extremes, though. It's important to remember that even in a "warm" month or a "cold" month that the temperatures often bounce around a lot:

No comments:

Post a Comment