Temperatures
For the last 30 years the average High on Halloween has been 4.5°C, and the average Low -3.7°C.
Last year in 2017 the High was a little below average at 3.8°C. But 2013-2016 were all above average with 2016 at 5.1°C, 2015 at 9.7°C, 2014 at 5°C and 2013 at 10.7°C.
The last time that we had a below-freezing High on Halloween was 2012 at -6.6°C, and with a Low of -9.1°C
For some trivia:
- Edmonton's warmest Halloween was 1981, which was way up at 19.9°C
- Edmonton's coldest Halloween was 3 years later in 1984, with a high of -18°C and a low of -24°C. 1984's High temperature of -18°C was lower than the Low temperatures of every other Halloween except for 1991.
- Since 1981 Edmonton hasn't recorded a Halloween above 15°C. But prior to that there had been 9 warm Halloweens.
- Prior to 1984 Edmonton hadn't recorded a Halloween below -15°C. But since then we've had 3 in 1984, 1991 and 2004.
Recent Rain & Snow
Last year's Halloween of 2017 wasn't particularly cold, but it was really wet: the International Airport recorded 3.6mm of Rain and 5.2cm of Snow.
Prior to that we'd gone more than a decade without snow on Halloween, with 2006 recording just a skiff of snow at 0.2cm.
The snowiest recent Halloween at the International was 1999, with 10.2cm of snow. At Blatchford that year only 2.2cm of snow was recorded, and it's snowiest recent Halloween was 1994 with 3cm (although Blatchford's records stop after 2007).
Historic Rain & Snow
Going further back into history, Blatchford's snowiest recorded Halloween matched the International's 10.2cm, but Blatchford set its record in 1882 while the International's was in 1999.
2017 actually ranked as the International's 2nd-snowiest Halloween with its 5.2cm, and also as the International's 2nd-rainest Halloween with its 3.6mm.
Snow-on-the-Ground
On October 31st the International usually does not have any snow on the ground. Recently 2017 had 2cm, and 2013 had 1cm.
But going back a bit further, 2001-2006 were really stand-out years for snow on the ground. 5 of those 6 years had 2cm-or-more of snow on the ground at Halloween.
On October 31st we usually don't have any snow on the ground, but over the next month that will change. November is when we typically start to get lasting snow, and on October 31st the average snowdepth is pretty close to 0cm, but by November 30th that average will increase to 10-15cm.
In this chart only 13 of the 56 years since 1961 had more than a dusting of snow on the ground on Halloween. But by the end of November that number flips to only 11-of-56 years without snow.
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