Saturday, January 12, 2019

2018 Summary

University of Waterloo Weather Station Annual Summary - 2018

Missing Seasons Alert!
If anyone knows the whereabouts of the Spring and Fall of 2018
please contact the UW Weather Station

Although this is a bit of an exaggeration, the year 2018 saw a rapid transition both between colder and warmer temperatures in May and then back again in mid-October.  Typically, both the Spring and Fall see times when the temperatures will swing between warmer and colder episodes, but this year it seemed like the transitions happened within a day.  It is hard to quantify just how unique this is, but by looking over the temperature graphs from the past 10 years I couldn’t see anything like it.

The year started out really cold, in fact the coldest temperatures of the 2018 occurred in the first few hours of the year on New Year’s Day.  These were followed by days with lows in the minus 20s, however just a week later there were days with highs over 10°C.  This oscillation of temperatures continued into February and included the high of 15.6°C on the 20th which was not only the highest February temperature in over 100 years of weather data in the region, it was also the highest temperature we saw until April 12th. 

Then came a good example of weather whiplash, with April setting the record for the coldest April in the region’s records followed by May which was the warmest.  Summer really started in May, a month which saw 8 days above 25°C (something that has only happened one other time during May) and another streak of 3 days over 30°C.

The warmer than average temperatures continued in June and July including the warmest June day since 2005 (on the 17th when it was 33.4°C) and 10 days in July over 30°C (the average is only 3.5).

But the real heat was still to come, as August was almost 3 degrees higher than average and the second warmest in the past 20 years.  This was followed by a September that was 3.5 degrees higher than average (the 5th warmest in the historical record) and gave us one heat wave with 5 days over 30°C followed by a second one with 5 more days that were over 25°C.

All this heat came to a crashing halt in mid-October with temperatures dropping by 10 degrees after the 12th.  The cold continued in November, which was the coldest since 1996 and the 5th coldest in the region’s history.  This colder pattern continued into mid-December after which we saw a bit of a warm up, resulting in the overall December temperature coming in at 2 degrees above average.

The 2018 overall average temperature was 0.9 degrees above the 1981-2010 average, but only just a little above the average for the last 10 years.

As for precipitation, the first few months of the year were wet with only March coming in drier than average.  One highlight was a period of 3 days in April with 72.6 mm of precipitation, which is almost as much as the average for the month.  This wet start to 2018 turned around in June which saw 12 dry days and a dry first half of July.  This brought the total for the year back into the average range where it pretty much stayed for the rest of the year except for a wet few weeks at the end of October.

The final total precipitation for 2018 of 950.1 mm was only a little over the average of 916.3 mm and well within the average range.

Frank Seglenieks
University of Waterloo Weather Station Coordinator

Summary for 2018:
Average Daily High Temperature: 12.71°C (average 12.05ºC)
Average Daily Low Temperature: 3.03°C  (average 1.94ºC)
Total Precipitation: 950.1 mm (average 916.3 mm)

(averages are calculated from 1981-2010 data for the Waterloo-Wellington Airport)

Click on the image below to see the temperature chart:

Click on the image below to see the precipitation chart:

Tuesday, January 1, 2019

December 2018 Summary

A warm December with average precipitation and low snowfall

After a start to the month that was a bit colder than average (except for the 2nd when it shot up to 13.5°C, the high temperature for the month), it was generally a bit warmer than average for the rest of December.  The overall average temperature came in at 2 degrees above the average.

A very rainy last few hours of the month pushed the total to just a half a mm above the average of 71.2 mm.  It shouldn’t be surprising with the higher temperatures that December only saw 11.5 cm of snow, much less than the average of 37.2 cm for the month.

Summary for December 2018:
Maximum Temperature 13.5°C
Minimum Temperature -12.7°C
Average Daily High Temperature 1.7°C (Long term average 0.2°C)
Average Daily Low Temperature -4.2°C (Long term average -6.8°C)
Total Precipitation 71.6 mm (Long term average 71.2 mm)

(Long term averages based on 1981-2010 data for the Waterloo-Wellington Airport)

Sunday, December 2, 2018

November 2018 Summary

A wet November that was the coldest in over 20 years

The colder temperatures that started in mid-October continued throughout November, with an overall temperature over 2 degrees below average it was the coldest November since 1996.  This put it at the 5th coldest in the over 100 year history of weather records in the region.  As well, the low temperature on the 22nd of -16.8°C was the coldest November temperature since November 23rd, 2000 when it was -17.9°C.

The total precipitation for the month of 93.4 mm was only a bit above the average of 87.1 mm, but enough to put into the above average range.  This puts the total for the year at 878.5 mm compared to the average of 832.9 mm.

The real story of the precipitation was the 21.5 cm of snow we received in the first half of the month, this is the most for the first half of the month since 1995 when we had 25 cm.  The rest of November only saw a little more resulting in a total of 23.5 cm, which is still a lot more than the average of 13 cm for the month.

Summary for November 2018:
Maximum Temperature 13.5°C
Minimum Temperature -16.8°C
Average Daily High Temperature 3.0°C (Long term average 6.3°C)
Average Daily Low Temperature -2.4°C (Long term average -1.4°C)

Total Precipitation 93.4 mm (Long term average 87.1 mm)

(Long term averages based on 1981-2010 data for the Waterloo-Wellington Airport)

Thursday, November 1, 2018

October 2018 Summary

A wet October with average temperatures

You can forget what the calendar said, fall really started this year on October 12th, you can see from the temperature graph just what a contrast there was between the first 11 days of the month and next 20.  In fact the average temperature during the first part of the month was 10 degrees higher than the second part.

Putting all those numbers together results in the overall temperature coming out exactly at the 1981-2010 average, although it may have seemed colder than that as it was the coldest October we have seen in the last 10 years.  The first time the temperature went below zero was on the 14th at 1:15 am (this is about the average for the last 20 years) resulting in a frost-free season of 167 days (which is just a bit longer than the average).

It was really wet at the start and end of the month, with over half of the month’s total of 94.2 mm coming during the first two days and the last day of the month.  As this month come in above average, it joins 9 of the last 10 years that were wetter than average.  This wet month also pushes the total precipitation in the first 10 months of 785.1 mm above the average of 750.6 mm.

Summary for October 2018:
Maximum Temperature 28.5°C
Minimum Temperature -2.6°C
Average Daily High Temperature 12.7°C (Long term average 13.5°C)
Average Daily Low Temperature 3.7°C (Long term average 2.9°C)
Total Precipitation 94.2 mm (Long term average 67.4 mm)

(Long term averages based on 1981-2010 data for the Waterloo-Wellington Airport)

Tuesday, October 2, 2018

September 2018 Summary

A very hot and somewhat dry September

The month of September saw 2 different heat waves, it started with 5 days of temperatures close to 30°C and then another 5 that were above 25°C around the middle of the month.  Although there were a few cooler days in between, the average temperature was almost 3.5 degrees above average.  This resulted in it being the 5th warmest September in the 100+ years of records in the region.

A couple of other random facts about this past September: The 5 days 30°C or over were the most since 1952.  The average low temperature was 4 degrees above average, this is the third highest in the historical record.  This month continues the pattern of warm Septembers we have seen recently, with only 1 in the past 20 years slightly below the 1981-2010 average and the rest above.

A dry 10 day period in the middle of the month resulted in the total precipitation (62.8 mm) coming in well below the average (87.8 mm).  The amount of precipitation we have seen so far this year of 690.9 mm is just slightly above the average of 683.5 mm.

Summary for September 2018:
Maximum Temperature 31.9°C
Minimum Temperature 3.4°C
Average Daily High Temperature 23.1°C (Long term average 20.4°C)
Average Daily Low Temperature 12.7°C (Long term average 8.6°C)
Total Precipitation 62.8 mm (Long term average 87.8 mm)

(Long term averages based on 1981-2010 data for the Waterloo-Wellington Airport)