It's not your imagination: the weather really is worse at weekends

Nice day for it. Image: Getty.

Do you ever feel that the weather is worse on the weekend? Well you might be right. Our research, published in Environmental Research Letters, shows that in Australia’s biggest cites, the temperature is on average up to 0.3℃ cooler on Sundays compared to Thursdays and Fridays.

Not only are humans affecting the temperature on a global scale, we’re also doing it in our own backyards.

There is nothing in nature that occurs on a weekly cycle. Therefore any weekly pattern seen in weather (such as temperature and rainfall) must result from human activity, such as generating electricity, powering motor vehicles and using air-conditioners.

Most of these activities deposit waste heat and pollution into the atmosphere, and weekly cycles in temperature provide valuable insights into the consequences of such activities on the urban environment.

Our study shows that weekly cycles in daytime temperature occur in almost all Australian major cities. Sundays are often the coolest, and Thursday or Friday, the hottest due to human activity. This differs according to the time of day, with early mornings showing a much stronger signal than the afternoon.

Rush hour weekly cycle

Early mornings are often associated with cooler air temperatures, which can trap any waste heat near the surface. By contrast, in the afternoon the temperature has warmed and the local surface heat can be carried away to higher levels. So we see less of a strong relationship between human activity and temperature.

Hence the 9am temperature is higher during the week (coinciding with the morning rush hour), and much cooler on the weekend (when the traffic volume is quieter).

Melbourne 1955-2013 average midnight and morning (9am) temperature Image: Nick Earl.

Melbourne and other major Australian cities are cooler at the weekend during the day, because they’re less busy. But what about night life?

In western cultures, with Saturdays and Sundays being days off work for a large proportion of the population, Friday and Saturday evenings have become popular with people going to restaurants, pubs, and theatres. This means there is more traffic and human activities in the city centres on these evenings through to the early hours of the following day.

Melbourne’s midnight temperature is warmest on Saturday (Friday night) and Sunday (Saturday night), which is the opposite to what we see for 9am.

Islands of heat

Cities are also generally warmer than their surroundings, a phenomena known as the “urban heat island” effect. Don’t rush off to the beach though – it’s only hotter in the city. We can see this in weekly temperatures by comparing city centres to surrounding suburbs.

When we compare Melbourne city temperature to the airport temperatures at Tullamarine, Laverton and Moorabbin, the city is a lot warmer than the airports, especially at night time. This difference is largest on Saturdays and Sundays, showing that Melbourne’s active night-life is increasing the urban heat island effect.

1972-2013 average difference between Melbourne city temperature airport temperatures at midnight and 9am. Image: Nick Earl.

The difference is less in the morning, especially on Saturdays and Sundays. There is even a small urban cool island on Sunday mornings compared to some suburbs.

Temperatures are closely linked to traffic volumes within cities. These can be used as a good indicator of the overall level of human activity.

Traffic volume at a typical Melbourne CBD junction during October 2014. Image: Nick Earl.

Consistent with traffic volumes (at a typical busy inner-city intersection), temperatures on Sunday mornings are much less than weekday mornings. It’s this difference in morning traffic that allows us to measure the difference of the city without cars (Sunday) and with cars (Monday to Friday) at the same time of day.

Figures show that traffic congestion costs about A$4.6 billion in Melbourne each year. Reducing this is high on the agenda for Infrastructure Victoria and the state government, putting forward numerous traffic reducing strategies including peak-time penalties for motorists and a London-style congestion charge for central Melbourne.

Beyond Victoria, the Australian government is concerned with the need to create cooler, greener and more liveable cities in the face of climate change.

Reducing traffic has obvious benefits for travel time and sanity – but our study shows that Melbourne is significantly cooler when traffic levels (and general human activity) are low, based on the weekly cycles of urban temperatures.The Conversation

Nick Earl is a postdoctoral associate in the School of Earth Sciences, University of Melbourne.

This article was originally published on The Conversation. Read the original article.


Coming soon: CityMetric will relaunch as City Monitor, a new publication dedicated to the future of cities

Coming soon!

Later this month, CityMetric will be relaunching with an entirely new look and identity, as well as an expanded editorial mission. We’ll become City Monitor, a name that reflects both a ramping up of our ambitions as well as our membership in a network of like-minded publications coming soon from New Statesman Media Group. We can’t wait to share the new website with you, but in the meantime, here’s what CityMetric readers should know about what to expect from this exciting transition.  

Regular CityMetric readers may have already noticed a few changes around here since the spring. CityMetric’s beloved founding editor, Jonn Elledge, has moved on to some new adventures, and a new team has formed to take the site into the future. It’s led by yours truly – I’m Sommer Mathis, the editor-in-chief of City Monitor. Hello!

My background includes having served as the founding editor of CityLab, editor-in-chief of Atlas Obscura, and editor-in-chief of DCist, a local news publication in the District of Columbia. I’ve been reporting on and writing about cities in one way or another for the past 15 years. To me, there is no more important story in the world right now than how cities are changing and adapting to an increasingly challenging global landscape. The majority of the world’s population lives in cities, and if we’re ever going to be able to tackle the most pressing issues currently facing our planet – the climate emergency, rising inequality, the Covid-19 pandemic ­­­– cities are going to have to lead the way.

That’s why City Monitor is going to be a global publication dedicated to the future of cities everywhere – not just in the UK (nor for that matter just in the US, where I live). Our mission will be to help our readers, many of whom are in leadership positions around the globe, navigate how cities are changing and discover what’s next in the world of urban policy. We’ll do that through original reporting, expert opinion and most crucially, a data-driven approach that emphasises evidence and rigorous analysis. We want to arm local decision-makers and those they work in concert with – whether that’s elected officials, bureaucratic leaders, policy advocates, neighbourhood activists, academics and researchers, entrepreneurs, or plain-old engaged citizens – with real insights and potential answers to tough problems. Subjects we’ll cover include transportation, infrastructure, housing, urban design, public safety, the environment, the economy, and much more.

The City Monitor team is made up of some of the most experienced urban policy journalists in the world. Our managing editor is Adam Sneed, also a CityLab alum where he served as a senior associate editor. Before that he was a technology reporter at Politico. Allison Arieff is City Monitor’s senior editor. She was previously editorial director of the urban planning and policy think tank SPUR, as well as a contributing columnist for The New York Times. Staff writer Jake Blumgart most recently covered development, housing, and politics for WHYY, the local public radio station in Philadelphia. And our data reporter is Alexandra Kanik, whose previous roles include data reporting for Louisville Public Media in Kentucky and PublicSource in Pittsburgh, Pennsylvania.

Our team will continue to grow in the coming weeks, and we’ll also be collaborating closely with our editorial colleagues across New Statesman Media Group. In fact, we’re launching a whole network of new publications this fall, covering topics such as the clean energy transition, foreign direct investment, technology, banks and more. Many of these sectors will frequently overlap with our cities coverage, and a key part of our plan is make the most of the expertise that all of these newsrooms combined will bring to bear on our journalism.

City Monitor will go live later this month. In the meantime, please visit to sign up for our forthcoming email newsletter.

As for CityMetric, some of its archives have already been moved over to the new website, and the rest will follow not long after. If you’re looking for a favourite piece from CityMetric’s past, for a time you’ll still be able to find it here, but before long the whole archive will move over to City Monitor.

On behalf of the City Monitor team, I’m thrilled to invite you to come along for the ride at our forthcoming digs. You can already follow City Monitor on LinkedIn, and on Twitter, sign up or keep following our existing account, which will switch over to our new name shortly. If you’re interested in learning more about the potential for a commercial partnership with City Monitor, please get in touch with our director of partnerships, Joe Maughan.

I want to thank and congratulate Jonn Elledge on a brilliant run. Everything we do from here on out will be building on the legacy of his work, and the community that he built here at CityMetric. Cheers, Jonn!

In the meantime, stay tuned, and thank you from all of us for being a loyal CityMetric reader. We couldn’t have done any of this without you.

Sommer Mathis is editor-in-chief of City Monitor.