World Cities Temperatures – 4 (Other)

This post refers to my analysis of recorded annual mean temperature trends at 7 stations located in large cities in “other” regions of the world, excluding Europe, USA and Asia.  The stations were all with long records (all over 95 years) and located in large cities (mostly with populations over a million).  The analysis used raw data (as recorded, without any adjustments) as published by KNMI (the Dutch Meteorological Institute). Polynomial curves of best fit were added to the plots.


Normally data from stations located in cities are not suitable for general studies of climate trends (except within urban areas!), because of the uncertain effects of urbanisation on the temperatures.  However, city data are often longer than rural data, and it is interesting to compare their long-term trends.  It is generally considered that urban temperatures have risen considerably during the past half-century due to increased development (roads, buildings, airports, etc) and increased air pollution (due to industrialisation and vehicles).  The urbanisation effect may vary considerably in different cities; for example, if a station is located near a coast there may be minimal urbanisation effect.  Another uncertainty with urban stations is that their locations may have changed over the years.  Also, prior to the introduction of Stevenson screens in the late 19th century, the instrumentation was different and this will also affect the apparent long-term temperature trends.

This selection of 7 “Other” cities is part of a larger analysis involving 50 cities, worldwide.

Plots are shown below for the 7 “Other” stations.  It should be noted that the polynomial fit line (in red) can sometimes be misleading at either end of the series as the line is very dependent on the temperature values in individual years (this sensitivity does not occur away from the start and end of the series).






Sao Paulo  










Please let me know what you think of my analyses.

The Author:

This article was written by Brian Gunter of Narooma, NSW, Australia. In his previous life Brian was an engineering hydrologist involved over many years in the analysis of rainfall and river flow data for the planning of water resources projects in Australia, Asia and Africa. In recent years he has been one of the Marine Rescue NSW (previously Royal Volunteer Coastal Patrol) volunteer weather observers who operate the Narooma station for the Bureau of Meteor


2 thoughts on “World Cities Temperatures – 4 (Other)

  1. Interesting that the mean temperatures of cities are rising at about 2 deg K / century while the world mean is rising by about 1 deg K / century. The extra rate could be the UHI effect rather than general climate. Most of the cities are still expanding rapidly as people leave the countryside.

    Good to see that you use data rather than processed values.


  2. Thanks for your comments Jack. My four posts showing temperature trends in 50 major cities was done as a side-issue only. Of course there are UHI effects in cities , but the effect seems to be variable. For example the apparent UHI effect in recent decades appears to be quite strong in places like New York, Sao Paulo, Sydney and Tashkent. However, the UHI effect is not so noticeable in places like Capetown, Dublin, Berlin and St Louis. Maybe these latter stations are located where they are not so influenced by urban features such as buildings, roads, pollution, etc. I don’t know!

    That is why most of my analyses have been confined to stations located in rural areas or small towns (250 stations worldwide) where the UHI effect is absent or at least less than in cities. Yes, I use only raw data and don’t make estimates of missing data. Also I claim that it is more meaningful to look at trends at individual stations (I did it for 250 stations!) rather than try to derive some sort of regional or world average trend. Last week the temperature reached 47 degC in some parts of Australia while it was about -30 degC in some parts of Canada, with most other parts of the world somewhere in between. So a “world average” temperature does not have any physical meaning and undoubtedly would hide geographical variations in trends.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s