July 2020 Review / August 2020 Preview

When you think back to the covid-summer of 2020, do you think you will remember the first 3 cool & rainy weeks of July, or the final hot one?

High Temperatures

The first few weeks of July 2020 weren't exactly cold, but there was a total lack of hot days.

The grey band in the middle of this chart is the 25th-75th percentiles for our High temperatures, which is where the temperatures will fall about half of the time. In the first part of the month July 1, 2, 7, 8, 12 & 13 were all below the 25th percentile and were pretty chilly for July. And only 1 day was actually above the 75th percentile into "hot" territory: July 16th at 27.1°C.

That all changed on July 27th when the temperatures finally (finally) jumped above average. They stayed there until the end of the month, and the forecasts say they will continue at least a little longer into August.

At the end of the month we finished with 17 days below average (including a 30-year coldest High), and 14 days above average.

In terms of the individual temperatures we didn't hit 30°C, but we did end up with 10 days at 25°C. That's below the July average of 12 days, but above years like 2019, 2011, 2010...

July 2020's average High of 23.4°C was on the cooler side of recent years, ranking as 12th warmest since 2000.

Hot Days So Far...

So far this summer we have had 14 days hit 25°C, which ties what we had last year in 2019. It's about 20-30 fewer than the very hot summers of 2015-2018, though. And it's a bit below the long-term average, which is about 20 Highs at 25°C by this point in the summer.

For slightly hotter days, we had our first 28°C High quite late on July 27th. We have now had 3 of those, while the average is around 6. And for milder 20°C days we have had 57, and that is below 2015-2018, but is pretty close to the long-term average.

Low Temperatures

The Low temperatures look a lot like the Highs, although at the end of the month we were right at the top of our 30-year range (and 0.1~0.2°C from the records).

The range of our July Low temperatures is usually very tight, and this year we had 4 nights below 10°C, 4 nights above 15°C, and everything else was between 10-15°C.

Warm & Cold Months

July 2020's average High of 23.4°C was just a bit below the recent average of 23.7°C and ranked as #67 our of 140. That average has stayed fairly level since records began in the 1880s, starting at 22.6°C, and rising as high as 24°C in the 1930s, and then dropping down to 22.4°C in the late 1990s.

July 2020's average Low of 12.9°C is right on the recent average, and ranks as #13 out of 140. While the July Highs have stayed fairly constant over the years, the average Lows have steadily increased from 8.5°C a century ago to about 13°C today.

Usually in these monthly reviews we talk about the mean temperatures (High & Low) of each month, but this is the middle of summer, and what people really care about are the Highs. So sticking with the Highs temperatures, in this chart the bubbles represent the average Highs for each month going back to 2000. These are compared to the 20th century average, and so big, orange bubbles were warmer than the 20th century average, and big, blue bubbles were colder.

You might notice that it has been a while since we have seen an orange bubble, because the last "warm" (above-average) Highs that we saw were back in February. Highs in March & April were both about 2°C below the 20th century average, and May, June & July 2020 barely show up here because they were so close to average.

So far during what we might call "summer" 2020 hasn't had any hot months, and it joins 2019, 2010, 2009, 2008, 2005, 2004 & 2000 which all had average-to-cool Highs for May through July. In 2019 that continued through August & September, and we didn't get another "warm" month until November. But hopefully August will turn things around for 2020.

Across the Country

Here we are taking a look at the Highs for July 2020 across the country, and there was quite a wide range. St. John's, Calgary & Vancouver were all 1°C or more below their 20th century averages, while Toronto, Ottawa & Montréal were 3.5~4°C above theirs.

 

This is a quick look at Toronto's Highs for July 2020. Their average High for the whole month was 30.3°C, which was the 2nd highest since 1880 (1921's average High was 31.2°C). Ottawa and Montréal are available in the dropdown on the upper right, and they look similar.

Monthly Precipitation

Heading back to Edmonton, and switching over to precipitation, in July Blatchford received 121.2mm which was its 27th rainiest July since 1880 (and below the 163.4mm in 2019). The International received 95.3mm, which was also its 27th rainiest, although those records only go back to 1960 (and it was also below the 118.6mm in 2019).

July's average precipitation is 90.8mm, so the International was just a bit above that, while Blatchford was above the 75th percentile and into the realm of "lots of rain." And looking at the chart June and May also both had lots of rain at both stations.

Blatchford's May-June-July total of 319.6mm was actually its 5th highest since 1880 (1901 leads with 410.4mm). The International's 310.1mm was its 3rd highest May-June-July since 1960 (2010 had 332mm).

Days With Rain

July averages 15 days with rain, and in 2020 Blatchford recorded 17 days while the International had 20. So it was not as rainy as it might have seemed. July is usually our rainiest month, and from mid-June through mid-July is our little monsoon season.

Precipitation So Far...

For 2020 so far the International has recorded 383.8mm of total precipitation (rain + snow), and Blatchford is just a bit below that at 374.5mm. The average for this time of year is 300mm, so we are definitely above average, and things really took-off in May, June & July after our very dry April.

August Temperatures

For August the daytime Highs are above 20°C most of the time, with typically about 25 warm days each month. We also average a week or two of days above 25°C, but 30°C days only happen about half of the time in August. For the Low temperatures it should be a lot of the same 10-20°C orange which we saw for July, but with a few more nights in the 5-10°C range, and every 5 years-or-so a night below 5°C. And also, August's average precipitation is about half of July's.

August 2019 was pretty blah, but that followed a string of warm years from 2011-2018. So hopefully last year was the anomaly, and summer 2020 actually hangs around for awhile this time.

Whitemud Creek and Sturgeon River

Today, something that is probably only of interest to me and handful of other people: we have a dashboard for the river levels in Whitemud Creek in Edmonton, and the Sturgeon River in St. Albert.

This dashboard shows the most recent readings from some of the stations around Edmonton. If you hover over each of the dots a graph of the recent depths and streamflows will appear.

Why are the depths and streamflows interesting?

Whitemud Creek and the Sturgeon are both paddleable throughout the spring and summer...but that is dependent on the water levels.

The province provides the data at https://rivers.alberta.ca/. That is a great site with some basic charts, and it provides near-realtime updates. But for data as spikey as creek levels average and quartiles don't give the whole context.

So this dashboard pulls the data from https://rivers.alberta.ca/ once per day, and it shows the daily maximum & minimum streamflows for all of the available years.

(A note about the depth for the Whitemud Creek at Rainbow Valley: it's waaaaay too high. I don't know what datum is being used, but the number never drops below 5m, and that is completely incorrect. I had thought that maybe it was measured relative to the same datum which is used for the North Saskatchewan, but that is not the case either. In a flood state like we just had the river measured 8m while upstream the creek depth was only at 6.6m.)

Late Summer

In the spring the water levels are reliably very high, but through July, August and into September they are generally quite low with occasional bumps from storms. 

With the government site it is difficult to know exactly what to expect later in the season, and so this chart shows how often the levels are high later in the season. And late-season spikes are common throughout July & August, but they only last about 3~4 days before the levels return to normal.

The Sturgeon

The data for these stations only goes back 10~20 years, and so there isn't a huge history. 

But just for some trivia, so far in 2020 the Sturgeon has been very high with a depth close to 2m and streamflow of 15m³/s. More typically in July the depth would be below 1.5m and the streamflow would be under 5m³/s. And in this chart if you click on the line for 2019 it was very high in August with a depth of over 2m and streamflow of 10m³/s.

This dashboard is definitely a niche interest. And if you need realtime data the https://rivers.alberta.ca/ site is a much better source. But for a more granular history and some context this dashboard can be handy. If you do find this dashboard useful the fullsize version here is probably better than the one embedded in this blogpost.

July 2020 Mini-Flood

With the recent rain there was some excitement on the North Saskatchewan this weekend:

On July 3rd the river peaked at a depth of 7.95m and a streamflow of 1,899m³/s. Just a few days earlier on June 30th it had been in a more normal range for this time of year at 5.1m and 635m³/s. So in 3 days the depth jumped by nearly 3m, and the streamflow tripled.

1,890m³/s+

With a peak of 1,899m³/s we didn't hit the 1,900m³/s mark. But since records began in 1911 on 16 years broke 1,890m³/s. Recently that included:

• June 24, 2013 was way up at 2,847m³/s and 9.25m.
• June 20, 2011 hit 1,897m³/s and 7.88m
• June 21, 2005 hit 2,612m³/s and 8.85m

The Biggest Floods 

This chart shows the largest recorded floods. Detailed depth measurement only started in 1999, which is why there is less history for the blue lines compared to the green:

• 1915 at 4,460m³/s and 13.73m
• 1986 at 3,990m³/s and 12m
• 1952 at 3,540m³/s and 10.59m

The 3-Day Rule?

The upper part of this chart compares the peaks of Edmonton's various big floods, and it shows what the streamflow was in the days just before and just after. (the lower part shows the rate of change from day to day).

For some reason, all of Edmonton's floods took 3 days or less to peak. 3 days before the levels were all in the normal~ish range of 800m³/s or less, then the big increases happened over 3 days, and on day 4 the numbers had started to drop. After a flood it usually takes a week or more for the levels to return to the normal range again.

None of these floods saw the levels jump up, then take a break or drop a bit, and then start climbing again to a new peak. It has always been a sudden ramp-up over 3 days, followed by a slower drop.

This "rule" isn't written in stone, because theoretically if a series of storms hit the province that could just keep adding more and more water into the system. But so far all of the major floods since 1911 have followed the 3-day rule.

Canada Day 2020

We are going to make this one quick:

Canada Day 2020's High of 17.9°C was:

• the coldest since 1974.
• the 16th coldest ever recorded.
• the 3rd Canada Day in a row below 20°C.

And also, we had 18.9mm of rain which made it the 3rd rainiest Canada Day on record.

Now let us never speak of it again.

June 2020 Review / July 2020 Preview

Today is our big review of the weather for June 2020.

How did it "feel" to everyone? Warm or Cold? Rainy or not? Let's take a look.

High Temperatures

June's High temperatures were fairly average, with 14 days above the 30-year average and 16 below it. On June 12th we hit a 30-year-warmest High at 27.9°C, although the record is up at 31.1°C from 1912. And then a week later on June 17th we hit a 30-year-coldest High at 13.6°C, and the coldest record there was 10°C from 1902. June 30th's High of 17°C came close to a 30-year-coldest High, but 16.9°C is the actual number.

The little bargraph at the bottom of this chart shows how the temperatures for June of each year compared to the 30-year average. For 2020 the Highs were just a bit colder than the 30-year average, and were a bit warmer than 2019. June 2015-2018 were all much warmer than the average, and before that June 2013 & 2014 were both relatively cold.

Looking at the numbers, June 2020's average High of 20.6°C was just a bit warmer than 2019's 20.3°C, and ranked as 12th warmest (or 8th coldest) since 2000.

We only had 3 days hit 25°C, compared to an average of 5 days for June. And we had 16 days hit 20°C, which was just a bit below the average of 17 days. We also had 2 days with Highs below 15°C, and that is right on the average for June.

Hot Days

For the year so far we have had 4 days hit 25°C, which is below the 6 that we had in 2019. But before that 2015-2018 all had a lot of hot days, and were up at 14-25 days by this point in the year.

The longterm average is around 7~10 days at 25°C by the end of June, so 2020 was a little low. We also have not had any days break 30°C or even 28°C yet this year.

For 20°C days we have recorded 29 so far. That matches 2019, and is pretty much average.

Low Temperatures

June's Low temperatures looked similar to the Highs, with 14 days above the 30-year average and 16 below. June 18th came close to a 30-year-coldest Low at 6.1°C, but everything else was comfortably within the typical range.

June's average Low of 10.4°C ranked as 10th warmest since 2000.

We had 2 Lows above 15°C, which is about average. And we had no Lows below 5°C, compared ot last year in 2019 when we had 4.

Warm & Cold Months

Here we have the average High temperatures for June going back to 1881. The average High has not changed much over the years, staying close to 21°C. 2020's average High of 20.6°C was below that average, although it was still above 2019, 2014, 2013 & 2011. It ranked 75th overall.

Here we have the average Lows for June, which have increased from about 7°C a century ago to 10°C today. 2020's average Low of 10.4 ranked as 22nd warmest overall.

Here we have combined the Highs & Lows, and each bubble represents the mean temperature for a month. Orange bubbles were warmer than the 20th century average, and blue bubbles were colder.

With June 2020's below-average Highs and above-average Lows the temperature overall was 0.8°C above the 20th century average, and so it appears as a small orange bubble. 2016-2018 were all warmer and appear as larger bubbles. And there are blue bubbles for cool Junes like 2000 & 2001.

June 2020's orange bubble follows an orange bubble for May, blue bubbles for April & March, and orange bubbles for February and January.

Across the Country

Across the country all of the cities which we look at had June temperatures warmer than their 20th century average. St. John's was 2.8°C warmer than its average; Toronto, Montréal & Winnipeg were all about 1.7°C warmer than their averages; and Regina & Vancouver were just 0.3°C above their averages.

The Year So Far...

This chart is really busy, but the red lines show how the daily temperatures for the year so far compare to the 20th century average.

If you add up each of the daily temperatures for January through June then so far 2020 has been 0.48°C warmer than the 20th century average, or Edmonton's 56th warmest year.

But most of that warming comes from the Lows, shown in the chart on the bottom in blue. The Lows have been 0.83°C above the 20th century average, while the Highs in orange have only been up by 0.12°C. That's similar to 2019, but very different from a really warm year like 2016 or 2017.

You can also use this chart to look at other cities, and for some examples Montréal is having a top-10 year, Winnipeg is top-30, and Calgary is pretty similar to Edmonton.

For one final look at how things have gone recently, here we are looking at the temperatures for the past 12 months, back to July 2019. In this chart each of the spokes on the big circle at the top represents how warm or cold the year was, and July 2019-June 2020 was 0.5°C warmer than the 20th century average. That put it in the 54th spot.

The circle in the middle of the bottom row shows how each day of the year compared to the 20th century average. There are large blue spikes for a few very cold weeks in January & April, and orange for our relatively ("relatively") warm November, late-December & late-January.

Monthly Precipitation

Was June 2020 rainy? Yes it was, but June is usually pretty rainy. It averages 75mm of precipitation, which makes it our 2nd rainiest month after July. In 2020 both stations above that with Blatchford at 106mm and the International at 117mm. That was Blatchford's 33rd rainiest June since 1881, and the International's 11th rainiest since 1961.

Last year June 2019 was also above average, with Blatchford at 117mm and the International a little lower at 86mm.

Here is a look at a few of the other cities around the country. 

Calgary was up at 172mm, which made 2020 Calgary's 9th rainiest June, and quite a bit above the 134mm which they recorded in 2019. And while we like to think of Vancouver as rainy, it actually usually gets less rain than Edmonton or Calgary in June & July. It recorded 52.6mm which is close to its average. Montréal recorded 46.4mm, which is quite low compared to its June average of around 90mm

Rainy Days Each Month

In June we average about 14 days with rain. This year we recorded a bit more rain than average, and the International also recorded more rainy days than average with 18. Blatchford was actually just below average with 13 days with rain.

The Rainiest Days

This chart shows the rainy days for Blatchford, and each bubble is a day with 20mm of precipitation or more. June 2020 had 3 of those (the bubbles furthest to the right) with 27mm on June 7th, 24mm on June 14th, and 24mm on June 30th.

If you switch this chart over to the International Airport, it also had 3 big days: 24mm on June 7th, 29mm on June 14th, and 33mm on June 30th.

Precipitation So Far...

Our total precipitation for the year so far is 253.3mm at Blatchford and 287.4mm at the International. Both of those are above the average of 207mm, and are also above the 74th percentile.

Looking at a few other cities around the country, so far in 2020 Calgary has had about 100mm more precipitation than Edmonton, with 357mm. Montréal's total is 470mm, while Vancouver is at 520mm.

This chart only shows those 4 season to keep it clean, but it includes data for 9 cities in total. At the extremes St. John's is all the way up at 663mm, while Winnipeg is down at 132mm and Regina is at 76mm. (I don't really know how accurate those last two are).

July Temperatures

So we have had another cool~ish start to summer in May & June this year, which was similar to 2019, and way down from warm years like 2016-2018. What could July hold? On average July has about 25 days which hit 20°C, including about 10 at 25°C. And 30°C doesn't happen every year, but only 6 of the past 20 July's didn't have any (that included 2019).

July is also usually our rainest month, with an average of 90mm, which is less that what we just got in June.