2019 new hottest and driest year

At Manilla, NSW, in the twenty years from 2000, the year 2019 was the hottest and the driest, overtaking the year 2018.

Climate logs Manilla 20-years

Climate records kept at 3 Monash Street, Manilla from April 1999 yield these eight graphs of climate variables. The graphs on the left (red) show heat and those on the right (blue) show moisture.
These graphs show the figures for calendar years, not for seasons.
In general, the temperatures in this 20-year record rose, with a pause between 2004 and 2012. Moisture peaked about 2010.
At Manilla, a sudden rise in temperature and fall in rainfall happened after 2017, having been much slower before that.
Dashed horizontal lines mark the normals for the decade from April 1999.

Left column graphs (red)

Yearly Mean Maximum Screen Temperatures

Day temperatures are shown by the mean maximum temperature in the Gill-type thermometer screen. The year 2019, at 27.91°, had the hottest days by far. The year 2018 had 27.13°, and 2002 and 2014 were almost as warm.The coldest days were in 2008 (24.57°) and 2010 (24.60°), followed by 2001 and 2011.
The 4th-order trend line shows a minimum about 2010, followed by a rapid rise.

Yearly Mean Screen Temperatures

This graph shows warmth in general, as in the study of global warming. Daily maximum and daily minimum temperatures are averaged. The year 2019 was the warmest (19.83°), followed by 2018, 2014, and 2009. The coolest year in this century was 2008 (17.19°), followed by 2001, 2011, and 2012.
The 4th-order trend line shows near-constant temperature from 2000 to 2011, followed by a rapid rise.

Yearly Minimum Screen Temperatures

Night temperatures are shown by the mean minimum temperature in the thermometer screen. While 2018 had not had very warm nights, 2019, at 11.75°, had warmest nights as well as days. The next warmest were in 2014, 2010 and 2009. Years with nights cooler than 10° on average were 2012, 2008, 2006 and 2001.
The 4th-order trend line shows a rise from 2000 to 2008, then near-constant temperature to 2014, followed by a rapid rise.

Yearly Subsoil Temperatures

Yearly temperatures in the subsoil (at 750 mm depth) hardly related at all to air temperatures read in the Gill Screen. The best match is in 2008, when the subsoil temperature was lowest (19.00°), as were the screen mean (17.19°) and the screen maximum (24.57°).
[Note that world temperature was low late in 2007.]
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2019 Climate by months

Monthly temp and rain 2019

The climate at Manilla, NSW,was extremely hot and dry in nearly all the months of 2019.

Mean temperature

In a normal year (See note below: “Manilla temperature Normals”), Manilla’s mean temperature has a cycle close to a sine-wave , being highest in January (25.9 deg) and lowest in July (9.5 deg). In 2019, the shape differed only in June being cooler than July.
Remarkably, every month of 2019 was warmer than normal. June, August and September were warmer by less than 1 deg, but December was 3 deg warmer, and January 5 deg warmer.

Monthly rainfall

Normally, Manilla’s monthly rainfall pattern (see note below) has two modes, with a main peak in January and a second peak in June. In 2019 there was no such pattern. Rainfall in most months was about 40 mm below normal, and was even lower in January, February and December. Only March and May had rainfall somewhat above normal.


Manilla Temperature Normals

The town of Manilla, NSW, had no recognised record of temperatures. When I had collected data for more than a decade, I felt the need to set up “normals” to compare actual values with those that are usual.

[Earlier, I quoted various official definitions of climatic normals in this post.
A climate normal is commonly taken as an average over three decades. To serve my purpose, I judged that a decade of data would be sufficiently stable.]

I based my normals on temperatures observed through the decade beginning 1 March 1999. I found mean values for the (366) days of the year, then made a more regular curve by using first, second and third harmonics.

Manilla temp normals

The graph shows mean maximum, mean average and mean minimum curves, as well as the resulting curve of daily temperature range. Numerical values that were posted earlier are repeated here:

Manilla’s dates of expected highest and lowest air temperatures during the year are marked on every “Weather” graph that is included in a monthly weather report in this blog. Each graph has curved dashed lines showing the “Normal” temperatures (Maximum, Mean, and Minimum) for each day of the year. The highest and lowest values in the annual cycle are marked on these curves. This list gives the dates of peaks and troughs and their seasonal lags in days after the solstice.
Highest daily maximum temperature (34.04°): January 20-21 (lag 31 days);
Highest daily mean temperature (26.19°): January 25 (lag 35 days);
Highest daily minimum temperature (18.44°): January 31 – February 1 (lag 42 days);
Lowest daily maximum temperature (16.91°): July 8 (lag 17 days);
Lowest daily mean temperature (9.35°): July 10 (lag 19 days);
Lowest daily minimum temperature (1.78°): July 13 (lag 22 days).

Apart from the peaks and troughs, one can see that the curves show a steeper rise in early spring. The rise is more marked and earlier for the maximum curve. This results in a wider daily temperature range at that time.

Manilla’s monthly rainfall pattern

As my normals for the rainfall of calendar months, I have adopted the mean values recorded in the 125 years 1884 to 2008 at Manilla Post Office, Station 055031. Values are shown in this table:

Manilla monthly rain normals.

Model of seasonal rainfall, ManillaIn the post of 20 June 2013, “A Seasonal Rainfall Model for Manilla, NSW”, I showed that the observed seasonal pattern fits very well to a model of two Gaussian curves of almost equal width but unequal height. The higher (summer) curve peaks at 84 mm/month near 27 December, while the lower (winter) curve peaks at 42 mm/month near 27 June. The peaks lag just 6 days after the solstices, and do not show the long and unequal seasonal lags that are seen in temperature data (above).

[There are discrepancies of less than 1 mm in monthly rainfall normal values between the table above and those cited in 2013. As the normal period, I replaced 1883 to 2007 with the more secure period 1884 to 2008.]