Mid-December Update

We don't normally do mid-month updates around here, but this December feels like it's worthy of some discussion.

50 Warmest Days for December 7-13

December has all been warm so far, but the peak of the heatwave was really from the 7th through the 13th.

The forecasts had made it sound like we might break some all-time records, but in the end that didn't happen. Notably, Edmonton's longest-standing record of 10.6°C from December 12, 1880 remained unbroken with 2017 coming in just a touch cooler at 10.0°C.

We did have 4 days in the Top-50 though, which is the most for any year. And that brings the 2010's to a total of  8 days in the Top-50. That's still below the 10 days during the 1890's, but the 2010's still have two more years to go.

High Temperatures

The heatwave actually started on November 23rd, so right now it's been going for just over 3 weeks. We haven't set any all-time records, but so far in December we've set 3 recent records, going back to 1996.

I often like to stress that warm temperatures during Edmonton's winters are not unheard of, and in any "typical" December we'll have at least a week of Highs above freezing. There are some years like 2010 and 2009, with 0 and 1 day respectively, but there are other years like 2011 and 1999 which had 19 and 22.

At the mid-way point of December 2017 we've had 15 days above freezing and 8 days above 5°C, and that's definitely on the warm side of things. We're well above the average, and in roughly the same range as the monthly totals for 2006, 2005 and 2004. We're still below 2011 and 1999 though, but with two weeks left in the month who knows what the weather has in store for us?

Days in a Row Above Freezing

On December our High was -3.7°C, but since then every day has had a High above freezing. As of December 16th that makes a string of 13 days, and from the forecast it looks like that might continue a bit longer.

This chart shows other long stretches of December days above freezing:

• 1898: December 15-28, 14 days
• 1939: December 1-20, 20 days (although that streak actually started in November and lasted a total of 41 days)
• 1954: December 10-22, 13 days
• 1985: December 13-26, 14 days
• 2002: December 5-18, 14 days

We're still a week from the all-time record of 20 days in 1939, but otherwise we're right near the top of the list.

Low Temperatures

Low temperatures aren't as much fun as Highs, but we have set 3 recent-records for warmest-Lows

Even with the warm temperatures this year, so far we haven't had any overnight Lows above freezing. Some of the other Decembers here - 1999, 2004, 2005 - had a few of those.

Snowdepth

The warm temperatures have brought some significant melting, and on the 14th Blatchford dropped to "trace" amounts of snow on the ground, and then back up to 1cm on the 15th. But that's down from 10cm on December 5th, and from 12cm when the heatwave started back on November 23rd.

The International has seen some melting too, falling from 20cm on November 23rd down to 9cm on December 13th and staying level for the 14th and 15th.