3-year trends to December 2019

December dry and very hot

3-year trends of climate anomalies

December raw anomaly data (orange)


Daily maximum temperature anomaly (all x-axes) extremely high: now five degrees above 21st century normal and three degrees above the record for smoothed values.
Daily minimum temperature anomaly (lower left): very high, just above the record smoothed value.
Subsoil temperature anomaly (lower right): still near normal.

Moistures (moist is at the bottom)

Rainfall anomaly (upper left): extremely low.
Cloudiness anomaly (upper right): extremely low.
Dew point anomaly (middle left): still rather low.
Daily temperature range anomaly (middle right): very high.

 Fully smoothed data values (red) 

Smoothed anomaly values now include June of 2019. From the rather static values of the spring, nearly all smoothed values for June began to move in the direction towards drought that seems to have prevailed since then.
There were two exceptions. Daily minimum temperature anomaly continued to fall very rapidly. Subsoil temperature anomaly approached a peak value.

Detail of rainfall vs. max temp

Rainfall and temperature anomaly trendsThe relation of smoothed rainfall anomaly to smoothed daily maximum temperature anomaly (top left graph) is important, but the graph is hard to read. I have drawn a part at a larger scale here.
The value for September 2017 is the first to show the current drought by falling on the hot-dry side of the normal range (aqua). Values became successively warmer and drier until March 2018 (max temp) and May 2018 (min rain). Values (especially temperature) then cycled away from drought until August-September 2018, and back to record-breaking drought in January 2019.
After January 2019, there was a retreat from drought until May 2019, when anomaly values were like those of 17 months earlier, in January 2018 (red square).
June 2019 began a renewed cycle towards drought, seemingly confirmed by later data.


January data points are marked by squares.


Smoothing uses Gaussian functions.
For fully smoothed data the function has a Standard Deviation of 2.5 months, it spans 13 monthly data points, and has a half-width of 6 months, which suppresses cycles shorter than 12 months. For partly smoothed data, the span of the function is reduced to 11 months, 9 months and so on.

Fully smoothed data points are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange.

Limiting values

Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

 * Normal values for rainfall are based on averages for the 125 years beginning 1883.

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