May 2017 is in the books, along with meteorological spring as a whole. Both were rather busy and a far cry from last year’s super Nino-influenced transition season.

Let’s dig right in, shall we? Maybe grab a snack or drink because this could take a while.

May 2017 500mb height anomalies:


May temperature anomalies:


May precipitation anomalies:


May temps vs forecast:


May precip vs forecast:


Stats breakdown by select locations (normals).

YZF Yellowknife NWT

Mean temp 8.4c (4.6c)

Rainfall 21.4mm (13.8mm)

Snowfall 1.2cm (4.7cm)


YVR Vancouver BC

Mean temp 12.8c (12.8c)

Rainfall 102.2mm (65mm)

Snowfall 0cm (0cm)


YYC Calgary AB

Mean temp 12.7c (9.7c)

Rainfall 38.1mm (46.1mm)

Snowfall 0cm (11.9cm)


YYZ Toronto ON

Mean temp 12.6c (13.1c)

Rainfall 142.6mm (74.3mm)

Snowfall 0cm (0cm)


YOW Ottawa ON

Mean temp 12.2c (13.3c)

Rainfall 176.8mm (80.1mm)

Snowfall 0.8cm (0.2cm)


YUL Montreal QC

Mean temp 13.1c (13.4c)

Rainfall 124mm (81.2mm)

Snowfall 0cm (0cm)


YQM Moncton NB

Mean temp 10.8c (10c)

Rainfall 163.5mm (92.5mm)

Snowfall 0cm (3.8cm)


YYG Charlottetown PEI

Mean temp 9.5c (9.2c)

Rainfall 160.4mm (87.2mm)

Snowfall 0cm (3.7cm)


YHZ Halifax NS

Mean temp 10.3c (10c)

Rainfall 156mm (109.8mm)

Snowfall 0cm (2cm)


YYT St. John’s NL

Mean temp 3.9c (6.4c)

Rainfall 38.4mm (97.9mm)

Snowfall 7.6cm (4.4cm)

This was another very wet month in many regions. It was the 4th wettest May on record for YHM Hamilton ON and YYZ Toronto ON, the 3rd wettest for YYG Charlottetown ON and the number 1 wettest for YOW Ottawa ON. This extends even farther back beyond YOW’s stats and bests 1916’s 175mm from the previous Ottawa station.

Exceptions were through parts of the Prairies and Atlantic Canada. YYT St. John’s NL had it’s driest May since 1989.

The west experienced some notable warmth as YYC Calgary AB saw it’s warmest May since 1958. The GL overall saw it’s coolest May since either 2008 or 2009, depending on the specific location.

With respect to spring 2017 defined as Mar-Apr-May, here’s the summary.

Spring 2017 500mb height anomalies:


Spring temp anomalies:


Spring precip anomalies:


Once again excessive moisture was a running theme. The west coast & Maritimes saw enhanced precip but ON and especially QC were the epicenters for damaging spring flooding. Southern portions of SK and MB were some of the areas coming out drier than normal.

90-day accumulated precip from March 3rd to May 31st:


90-day precip expressed as a departure from average values, same timeframe:


Highlighting the situation via some airport stats, here are the combined Mar-Apr-May precip totals against normals. Note that this version of precip combines both rain and snow amounts.

YVR Vancouver BC

Spring precip – 442.2mm

Average – 267.4mm


YYC Calgary AB

Spring precip – 121.6mm

Average – 99.8mm


YYZ Toronto ON

Spring precip – 321mm

Average – 192.6mm


YOW Ottawa ON

Spring precip – 412.2mm

Average – 219.2mm


YUL Montreal QC

Spring precip – 398.4mm

Average – 232.5mm


YHZ Halifax NS

Spring precip – 376.5mm

Average – 346.5mm


YYT St. John’s NL

Spring precip – 271.4mm

Average – 367.7mm