This post refers to my analysis of recorded monthly mean temperature trends at the small town of Moruya Heads in southeastern Australia. The station was established in 1893. The analysis used raw data (as recorded, without any adjustments) as published by BOM (the Australian Bureau of Meteorology). Polynomial curves of best fit were added to the plots.
The town of Moruya Heads is located the coast in southeastern New South Wales.
Temperature records commenced in 1876, but the data prior to 1910 was inconsistent with later data (possibly due to different instrumentatiuon Over the 1910-2016 period (a period of 107 years) the years are 94% complete.
Moruya Heads has an temperate coastal climate with mild winters and mild summers. Mean monthly temperatures vary from 11.1 degC (in July) to 20.2 degC (in February). Extreme monthly mean temperatures recorded are 9.4 degC (in July 1968) to 22.0 degC (in February 2010).
Mean, Maximum and Minimum Monthly Temperatures
Plots are shown below for annual mean temperature and the monthly mean temperature for each of the 12 months. A polynomial trendline was fitted to each graph. A comparison of the monthy trendlines are also presented. It should be noted that the trendlines (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).
Annual Mean Temperatures
Monthly Mean Temperature Trendlines
- The plots show a variable, often non-cyclical monthly trendlines in most months with Highs around 1910 and 2010 and a Low around 1960.
- The monthly temperatures around 2010 are generally between 0.0 degC and 1.0 degC higher than those around 1910.
- The monthly temperatures around 1960 are generally between 0.0 degC and 1.0 degC lower than those around 1910.
- A plateau in the trendline around 2000/2010 is observed to occur in most months.
- The average annual temperature trend since 1910 is about +1.0 degC/century.
- There are no alarming increases in the temperature trendlines in recent decades.
Moruya Heads is one of 257 stations, worldwide, for which I have analysed long-term temperature trends. The analyses at 50 representative stations are summarised in the blog post: world-50-temperatures
Please let me know what you think of my analyses. firstname.lastname@example.org
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 Australian Bureau of Meteorology.