SA now experiencing half- year summers

DATA on daily maximum and minimum temperatures was collected from 35 meteorological stations of the South African Weather Service, covering the period between 1980 and 2015.

Gone are the days when we as South Africans would experience a three- month spring season, easing into summer, and then cooling off for three months before we hit winter.

As lecturer in the Department of Geography at the University of the Free State, I focused my research on biometeorology ( a specialist discipline exploring the role of climate change in physical and human environments) as well as climatology and geographic information systems.

I recently published an article, “Statistical classification of South African seasonal divisions on the basis of daily temperature data” in the South African Journal of Science.

In this study, which I undertook with Jennifer Fitchett, a colleague from Wits University, we went to great lengths to ensure that we had a complete set of data before presenting it to demonstrate seasonal brackets.

Our statistical seasonal brackets indicate that South Africans now experience longer summers ( from October to March), autumn in April and May, winter from June to August, and spring in September. Although much work has been done using rainfall to determine seasonality in Southern Africa, I believe these methods did not work well as there are too many inconsistencies in this approach.

To make matters more complicated, as a semi- arid region and with desert conditions along the West Coast, some regions do not have enough rainfall to use as a classifier.

Temperature, on the other hand, worked well in this study.

“Temperature is a continuous variable, and in Southern Africa has sufficient seasonal variation to allow for successful classification.

“Although several international studies used temperature metrics to statistically classify their seasonal divisions, this study would be the first known publication in a South African context using temperature as a classification metric.”

We believe that a clearly defined and communicated method should be used in defining seasons, rather than just assigning months to seasons.

One of the most important arguments of our work is that one needs to critically consider breaks in seasons, rather than arbitrarily placing months into seasons.