April 2019 Review / May 2019 Preview

Today we are going to take a quick look back at a relatively quiet (although snowy) April.

But first, we are going to start with this chart again:

Cliquez pour une version en plutôt mauvais français.

Aujourd'hui nous parlons un peu d'un mois de avril assez typique.

Mais d'abord on commence de nouveau avec cette graphique:

We've said it before, and we'll say it again: during May we get at least one notable (1cm+) snowfall half of the time. So while these last few snowy days of April are feeling like 2nd winter, there might be more to come. Anyway...

Avril est vraiment terminé, mais pour la neige ce n'est pas nécessairement le cas. La moitié du temps en mai nous aurons aussi au moins une jourée avec 1cm+ de neige. Malheureusement, c'est la vérité.

High Temperatures

The High temperatures for April were fairly close to average, with a few warm weeks early on, and then things cooling off a bit at the end. We were in the typical range though, and didn't hit any extremes.

Les températures maximales d'avril étaient presque moyennes. Au debut du mois il faisait un peu chaud, et pendant la dernière semaine il faisait plus froid. Mais nous avons évité les extrêmes.

Looking at the numbers, we had one High above 20°C, with the 22nd hitting 22.6°C. Some Aprils (like 2017) don't have any of those, but the average is 2, and last year we had 4. Our 6 Highs above 15°C was also just a bit below the average of 7.

We didn't have any Highs below 0°C this April, compared to 9 (9!) last year. We average 2 Highs below freezing in April, but that's split so that half the time we don't have any, and the other half have longer coldsnaps.

Avril a eu un jour chaud, avec une température maximale de 22,6°C le 22ème. Parfois le mois d'avril n'en a pas, mais la moyenne est 2, et en avril dernier nous en avions 4. Et cet avril nous n'avons pas eu de températures maximales inférieures au point de congélation, alors que la moyenne est de 2.

Low Temperatures

And like usual, the Low temperatures follow a similar path to the Highs with a warm start to the month, and things cooling off at the end. The 10th did hit a warmest-since-1996 Low of 4.6°C.

Comme d'habitude les températures minimales suivaient les températures maximales, avec un départ assez chaud et une fin un peu froide. Le 10ème a eu une température minimale de 4,6°C, qui était le plus chaude depuis 1996 pour cette date.

For the Lows we had 18 below freezing, compared to a recent average of 16. But we only had 1 Low below -5°C, and the average is 5. Looking back at last year again, the very cold April started with a weeklong coldsnap that included 3 Lows of -18°C.

Il y a eu 18 températures minimales inférieures au point de congélation, par rapport à une moyenne de 16. Mais il n'y a pas eu de jours très froids contrairement au mois d'avril dernier qui avait commencé avec une semaine en dessous de -10°C.

Warm & Cold Months

When we add up all of the Highs and the Lows the average temperature for April 2019 was 5.6°C, which ranks as 52nd warmest out of the 138 years since 1881. That's above 2018 & 2017, but below 2016 & 2015.

The average High of 11.3°C ranks as the 61th warmest High, and the average Low of 0°C is 39th warmest.

Looking at the 10-year average (dotted red lines) we can see that April's average High has actually dropped a bit over the years, from about 11°C down to 10°C. But at the same time the Lows have increased from about -3°C to about -1°C. We looked at that strange behaviour (October does the same thing) in detail in The Months through the Years.

En combinant les températures maximales et minimales cet avril a eu une température moyenne de 5,6°C qui se classe au 52ème rang des plus chaudes depuis 1881. C'est plus chaud que 2018 & 2017 mais plus froid que 2016 & 2015. Et la température maximale moyenne de 11,3°C est la 61ème plus chaud alors que la température minimale moyenne de 0°C est la 39ème plus chaud.

Our pretty boring #52 April follows an equally boring #49 March, but before that we had our 5th coldest February, and 16th warmest January.

Mars et avril ont été tous les deux plutôt tranquilles en comparaison à notre février tres froid et janvier presque chaud.

And here is a snapshot of the months for the last 20 years. Our cold February stands out, but that was followed by a slightly warmer-than-average March & April. That follows colder-than-average Marches & Aprils in both 2017 & 2018.

Et nous avons ici tous les mois des 20 derniers années, à nouveau.

Snow

The International Airport's 11cm of snow this April was really late in the month, but overall it was less than last years 12cm, and below the April average of 15cm.

The late April snow bring our total for the winter to 155.2cm, which is above the 75th percentile for recent years, so it's pretty high.

On thing that's interesting here is the large, 50 day gap from our last, true, "winter" snow on March 8th, to the appearance of spring snow on April 27th. In comparison, the red line for last winter is full of dots representing snowfalls during March and early-April.

Once the snow is all finished we will do another big series of snow charts for the winter of 2018-2019.

Precipitation

For precipitation in general (snow&rain) this was a fairly dry April at the International, with only 12mm. That's below last year's 16mm, and below the average of 30mm. Blatchford only recorded 4mm, but in recent years it has tended to record less than the airport.


May Temperatures

And finally, here is a quick preview of what temperatures might look like in May.

Last year May 2018 was incredibly warm: it was the warmest May since 1880, and it's average temperatures were more like a typical July. We looked at it in detail here.

More generally, May has not had a High below freezing since 1959, so that's nice. But about one third of the time we will have a few days that stay below 5°C. On the other side of things we should probably see a week or two of days above 20°C (2000 was the only real under-achiever, with 2 20°C days). 2015, 2016 & 2017 all had almost a week of 25°C days, while 2018 had almost 2 weeks. And 2013, 2016, 2017 & 2018 each had a High of 30°C.

For Low temperatures, about a quarter of the time our final frost will be in April, and so May will have no Lows below 0°C. More typically though, May will have a handful of frosty nights.

Et enfin, voici l'histoire récente des températures pour mai. Mai dernier a été le mai le plus chaud jamais enregistré depuis 1880. Plus typiquement le mois de mai aura une ou deux semaines avec des températures de 20°C. En 2015, 2016 & 2017 il y'a eu presque une semaine de 25°C, tandis qu'en 2018 il y a eu presque deux semaines. Et récemment nous avons atteint 30°C en mai en 2013, 2016, 2017 & 2018. Pour les température minimales, un quart du temps la dernière gelée aura lieu en avril, mais le reste du temps ce sera en mai.