Tuesday, January 14, 2020

2019 Summary

University of Waterloo Weather Station Annual Summary - 2019

First half of 2019: cold and wet
Second half of 2019: (mostly) warm and (mostly) dry
Overall for 2019: average temperature and precipitation

As you can see above, there were really two parts to the weather story for 2019 in the Waterloo Region.  The first half of the year didn’t have any above average months for temperature or below average months for precipitation.  In the second half of the year, 5 of the 6 months were above average for temperature and only 1 month that was wetter than average.  When you put that all together, you come up with a year that was very average.

At 1.5 degrees below average, January started off the year cold including the 30th when it only got up to -17.2°C, this was the lowest daily high temperature since Feb 19, 2015.  February and early March saw a lot of variation in the temperature with some warmer spells and cold patches.  It wasn’t until about mid-March before we experienced a few weeks of generally average temperatures.

Then we had what has been typical in the last few years, with colder than average Spring temperatures, particularly in April.  Although it was never really extremely cold during this time, there were a lot of days enough below average to result in a colder than average April and May.

June was the first month of year that was at least a little bit higher than average (even if it was just by 0.04 degrees).  This started off the warm summer, which peaked in July when it was over 2 degrees higher than average, making the hottest month since July of 2012, also that month had 9 days over 30°C which is well above the average of only 3.5 days.

Continuing the pattern we have seen for the last 20 years, September was warmer than average, even though it was the least warm September in the previous 6 years, it was still 2 degrees above average. October started off with a daily high temperature near 30°C, which was only the third time there has been a day of at least 30°C during the month of October in the over 100 years of weather data in the region.  Overall October was 1.2 degrees above average.

November was definitely the anomaly for the second half of the year, coming in at 2.5 degrees colder than average, enough to make it the coldest in the past 25 years, while the high temperature of 10.4°C on the 27th was the lowest daily high temperature for November on record.  It then turned around in December with a generally warm month that was 1.5 degrees above average.
 
So when you combine the colder first half of the year with the warmer second half, it not surprising that the result is an overall temperature just 0.1 degrees above the average, which is the least warm overall temperature since 2014.

As for precipitation, it was above average from February to May, but then it got a little bit drier, with July the driest month of the year with only 39.8 mm.  Although the wettest month was October (152.4 mm) it was an outlier in an otherwise drier than average second half of the year.

The final total precipitation for 2019 of 923.0 mm was only a little over the average of 916.3 mm and well within the average range.  Fun fact, this was the closest final total to the average in the 20 year history of the UW weather station.

Frank Seglenieks
weather@uwaterloo.ca
University of Waterloo Weather Station Coordinator

Summary for 2019 (averages from 1981-2010 data for the Waterloo-Wellington Airport):
Average Daily High Temperature: 12.28°C (average 12.05ºC)
Average Daily Low Temperature: 1.95°C  (average 1.94ºC)
Total Precipitation: 923.0 mm (average 916.3 mm)

Extremes for 2019 (all time UW weather station extreme in brackets):
Highest temperature:
33.2°C Jul 5 4:00 pm (35.7 °C July 21, 2011 3:00 pm)
Highest humidex:
43.4 Jul 5 4:15 pm (47.6 July 17, 2013 5:00 pm)
Lowest temperature:
-26.7°C Feb 28 6:45 am (-35.5 °C Feb 16, 2015 7:00 am)
Lowest windchill:
-39.1 Jan 31 7:45 am (-47.3 Feb 15, 2015 6:15 am)
Greatest temperature drop in 15 minutes:
-5.2°C Jun 28 12:00 pm (-9.5 °C July 19, 2013 5:00 pm)
Greatest temperature drop in 60 minutes:
-8.6°C Jun 28 12:00-1:00 pm (-11.8 °C July 19, 2013 4:45-5:45 pm)
Greatest temperature rise in 15 minutes:
3.8°C Jan 1 8:00 am (8.6 °C Jan 2, 2001 6:15 am)
Greatest temperature rise in 60 minutes:
8.0°C Feb 28 8:00 - 9:00 am (12.2 °C Jan 2, 2001 4:45-5:45 am)
Highest precipitation in 15 minutes:
12.8 mm Aug 18 4:45-5:00 pm (23.0 mm Jul 22, 2008 1:45-2:00 pm)
Highest precipitation in 60 minutes:
14.8 mm Aug 18 4:30-5:30 pm (36.7 mm Jun 16, 1998 3:30-4:30 pm)
Highest Precipitation in 1 day:
36.6 mm Aug 18 (78.0 mm July 11, 2008)
Highest 15 minute average wind speed:
22.5 km/h Feb 24 12:15 pm (44.6 km/h Mar 9, 2002 6:30 pm)
Highest wind gust (only available since 2015):
36.9 km/h Feb 24 12:15 pm (44.4 km/h Apr 13, 2015 2:30 pm)
Last time the temperature went below 0 before the summer:
Apr 29 6:30 am (Has ranged between Apr 26- May 23)
First time the temperature went below 0 after the summer:
Oct 19 12:45 am (Has ranged between Oct 2-29)
Length of frost-free season
173 Days (Has ranged between 146-175 days)
Highest daily low temperature:
22.2°C Jul 19 (25.3 °C Aug 1, 2006)
Lowest daily high temperature:
-17.2°C Jan 30 (-20.6 °C Feb 15, 2015)
Largest daily temperature range:
22.1°C Mar 1 (29.6 °C Feb 19, 2007)
Smallest daily temperature range:
1.7°C Feb 11 (0.45 °C Dec 7, 2005)

(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:

Wednesday, January 1, 2020

December 2019 Summary


A warm December with average precipitation

Apart from 8 hours of really cold temperatures overnight between the 19th and the 20th, the rest of the month was relatively warm.  This put the overall temperature at 1.5 degrees above average.  Interestingly, it seems that most of the recent Decembers have gone one way or the other, in the past 10 years we have had 6 above average, 3 below average, and only one average December.

There was pretty steady precipitation throughout the month and although the total of 57.0 mm was less than the average of 71.2 mm, it was still within the average range.

December only saw 19.0 cm of snow, about half the average of 37.2 cm for the month.

Summary for December 2019:
Maximum Temperature 10.1°C
Minimum Temperature -21.2°C
Average Daily High Temperature 1.9°C (Long term average 0.2°C)
Average Daily Low Temperature -5.5°C (Long term average -6.8°C)
Total Precipitation 57.0 mm (Long term average 71.2 mm)


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


Sunday, December 1, 2019

November 2019 Summary


A dry November that was the coldest in almost 25 years

For the second year in a row we had a very cold November, with this one coming in at 2.5 degrees below average and almost half a degree colder than last year.  This put it at the 6th coldest in the over 100 year history of weather records in the region and the coldest since 1996. 

These cold temperatures were most prevalent during the first 20 days of the month and even a warm up during the last 10 days couldn’t bring the overall temperature back into the average range.  One fun fact from the month was that the high temperature of 10.4°C on the 27th was the lowest high temperature for November on record (the previous lowest high was 11.8°C in 1997).

Although there was a steady amount of precipitation throughout the month with a little bit coming every few days, the total of 52.8 mm was well below the average of 87.1 mm.  The total we have had so far this year of 866.0 mm is not that much above the average of 832.9 mm, which means we are setting up to have an average year for precipitation overall.

It isn’t that unusual to get some snow in early November or even late October, but usually those are smaller amounts.  So the 12.5 cm of snow that fell during the 11th was the earliest date for over 10 cm of snowfall since Oct 31, 1997 when there was 12 cm.

The total snowfall for November was 16 cm, which is a bit more than the average of 13 cm for the month.

Summary for November 2019:
Maximum Temperature 10.4°C
Minimum Temperature -12.0°C
Average Daily High Temperature 3.4°C (Long term average 6.3°C)
Average Daily Low Temperature -3.6°C (Long term average -1.4°C)
Total Precipitation 52.8 mm (Long term average 87.1 mm)

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


Sunday, November 3, 2019

October 2019 Summary


A warm and very wet October

The month started off with a daily high temperature near 30°C (29.6°C to be exact), which was only the third time there has been a day of at least 30°C during the month of October in the over 100 years of weather data in the region.  The others were: Oct 8, 2007 (30.3°C) and Oct 6, 1946 (31.1°C).

This was followed by almost a week of temperatures in the low 20s to high teens, which was still warmer than average for that time of year.  With the rest of the month seeing average temperatures, the overall temperature for October was 1.2 degrees higher than average and we have now seen 4 months in a row with above average temperatures.

The temperature first went below zero on October 19th at 12:45 am, which is about a week later than the average for the 20 years of the UW Weather Station.  It also puts the frost-free period for 2019 at 173 days, about 12 days longer than the average. 

During the last week of the month there were 3 days with over 20 mm of precipitation, in fact just that week would have resulted in average precipitation.  Combined with the rest of the month the total precipitation of 152.4 mm was more than twice the average of 67.4 mm and the most in the last 6 years.

This wet month resulted in the total precipitation for the year (813.2 mm) going well above the average for this time of year (750.6 mm).

Summary for October 2019:
Maximum Temperature 29.6°C
Minimum Temperature -2.6°C
Average Daily High Temperature 14.9°C (Long term average 13.5°C)
Average Daily Low Temperature 4.0°C (Long term average 2.9°C)
Total Precipitation 152.4 mm (Long term average 67.4 mm)

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


Thursday, October 3, 2019

September 2019 Summary


Another hot and dry September

I always say there is never a sure thing when it comes to the weather, but for the past 20 years a really good bet has been that September will be warmer than average.  Although this was the least warm September in the past 6 years, it was still 2 degrees above the average. 

Apart from 3 days late in the month when the temperature was above 25°C there really weren’t any extended heat waves, just a lot of days a little warmer than average.  OK I know I’m really digging deep for this one, but the lowest temperature during the month was 5.7°C and I was not able to find another September with a higher minimum temperature in the 100 years of weather records in the region (the closest was 5.4°C in 2015).

A few storms during the first half of the month kept us moderately wet, but a week of no rain and only a few storms in the second half led to a total of just 44.8 mm, which is about half the average of 87.8 mm.  The last time we had a wetter than average September was back in 2014, in fact from 2010-2014 we had a streak of wetter than average Septembers and since then they have all been drier.

With this dry month, the total for the year of 660.8 mm is now slightly below the average of 683.5 mm for this time of year.

Summary for September 2019:
Maximum Temperature 29.0°C
Minimum Temperature 5.7°C
Average Daily High Temperature 22.2°C (Long term average 20.4°C)
Average Daily Low Temperature 10.8°C (Long term average 8.6°C)
Total Precipitation 44.8 mm (Long term average 87.8 mm)


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