December 2016 was hot

A bearded dragon camouflaged on a bush

Hidden Dragon

Hot weather in this month came in the first and last weeks which, on average, were 4.8° and 3.6° warmer than normal. On the 5th, both day and night were nine degrees above normal. There was just one 40° day, on the 30th. In December months from 1999, there have now been five with one 40° day, but none with more than one. The two hottest, at 40.6°, came in 2005 and 2012.
Rain fell frequently (on 12 days), but it was light (max: 17.8 mm). Plants dried out.
Throughout the month, tiny “flies” swarmed in millions. They are native Rutherglen Bugs (Nysius vinitor), a sap-sucking pest of crops such as sunflower.

 Weather log December 2016

Comparing December months

This was the hottest December of the new century. December 2009 had been the hottest, but this month had a higher mean daily maximum (33.8° vs. 33.1°) and a slightly higher average (26.0° vs. 25.9°). December 2009 still had the warmest nights: the daily minimum was 18.6° then versus 18.2° now. As this month’s days and nights were both so warm, the daily temperature range was quite normal (15.6°).
Contradicting the high air temperatures, the subsoil temperature was well below the normal value of 24.3°. At 22.7°, it was the coolest December value since 1999, when it had been 22.5°.
The month was rather cloudy, which does not match well with the rather low dew point and rainfall. The monthly rainfall total of 48.8 mm is in the 34th percentile, well below the average of 74 mm.

Climate fro December 2016

The Year 2016

As in 2015, the average temperatures for the year 2016 were close to normal by day, and half a degree above normal by night. The subsoil temperature, which had been normal in 2015, fell to half a degree low. Air temperatures had been warmer in 2014 and 2009, and cooler in 2008.
Rainfall, at 775 mm, was in the 76th percentile, well above the 125-year average of 652 mm. The mid-year months of June, August, and September were very wet, while November as well as February, March and April were dry. High rainfall is rare in mid-year months, but 1998 had a similar pattern.
Temperatures also were far from normal in some months. They were about 2° higher than normal through the autumn and 2° lower than normal through the spring.


Data. Rainfall figures are usually from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. However, the gauge ceased recording on the 8th of October, and later readings are from my non-standard gauge. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

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3-year trends to December 2016

Parametric plots of smoothed climate variables at Manilla
“December 2016 hot with cold subsoil”

3-year trends to December 2016

December raw anomaly data (orange)

In December 2016 both days and nights became hot, but the subsoil remained cold. Other variables were near normal. During the last six months all partially-smoothed anomaly values moved around the edges of the graphs.

 Fully smoothed data (red)

At the time of the latest fully-smoothed anomalies, in June 2016, most variables were moving rapidly towards cool and moist.
Daily minimum temperature and subsoil temperature, however, fell slightly from a peak in May. The subsoil temperature was normal, but the daily minimum temperature anomaly had reached a new record high for a smoothed value in May 2016: +1.34 degrees.

Subsoil temperature

The observed changes in subsoil temperature are a mystery. Generally, they are like those of daily maximum temperature, but with leads or lags as shown by curved arrows on the bottom right graph. They relate well to daily minimum temperature, as shown by the similar patterns on the bottom two graphs. This month, however, the raw anomaly of subsoil temperature is very low, while those of maximum and minimum air temperature are very high.


Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

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.

December 2015: normal month, normal year

Senna bush photo

Senna-leaf circles

Very few days or nights were more than four degrees from normal this month. The coldest day (the 23rd) was 24.9°, only 7.6° below normal.
Rain fell, mainly as showers, on nine days spaced through the month. The highest reading was 31 mm on the 10th.

Weather log December 2015

 Comparing December months

Nearly all climate variables were very close to normal. Those furthest from normal were:
Early morning dew point, 9.4°, below normal by 3.9°;
Daily minimum temperature, 17.1°, above normal by 0.7°;
Cloudy days percent, 45%, above normal by 14%.
The total rainfall of 101.9 mm was well above the average of 74 mm. It was almost the same as in last December (99 mm): in the 74th percentile, The two-month total for November and December was also high (176 mm). There are no serious rainfall shortages for totals for any number of months.

Climate for December 2015

The Year 2015

Compared to other years in the new century, this year had day temperatures that were on the average (25.6°), and nights (10.8°) that were just 0.6° above average. The subsoil temperature (20.1°) was also near average.
Like last year, the percentage of mornings with more than four octas of cloud (37%) was close to the recent average (40%) for 2007 to 2014, but much more cloudy than the earlier average (26%) for 2000 to 2006.
The rainfall, 621 mm, was only 31 mm below the long-term rainfall average of 652 mm.


Data. All data, including subsoil at 750 mm, are from 3 Monash Street, Manilla. Rainfall data up to 26/3/15 is from Manilla Post Office, Station 055031.

3-year trends to December 2015

Parametric plots of smoothed climate variables at Manilla
“December 2015: moist”

Trends to December 2015

December raw anomaly data (orange)

In December, raw values for daily maximum and daily minimum temperature anomaly, which had been very high in October and November, returned to normal. Rainfall and cloud became higher than normal.

 Fully smoothed data (red)

In the latest month with fully smoothed data (June 2015) no anomalies were changing much. Most were near cool/moist climate peaks (towards the lower left): only daily minimum temperature and subsoil temperature were near warm/dry peaks. None of these peaks had extreme values.


Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

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.

December 2014 rainy with warm nights

Photo of a rain-shower

A shower on Mt Baldwin

Few days or nights were unusually warm or cool, except for a very cold day on the 28th. Thunderstorm clouds were often seen, but only a few yielded any rain. Later, overcast skies brought steady rain recorded on the 27th (25.2 mm) , 28th (11.2 mm) and 29th (12.6 mm). There were fourteen rain days: twice the usual number.

Weather log December 2014

Comparing December months

The mean daily maximum temperature (31.8°) was normal, but the mean daily minimum temperature (18.0°) was very high (Very warm nights!), just below the record of 18.6° set in 2009.
Subsoil temperature (24.7°) fell to normal after two Decembers above normal.
The total rainfall of 99.0 mm was in the 72nd percentile, well above the average of 74 mm. This clears most of the shortages in rainfall totals for groups of months. Two serious shortages remain: the nine month total of 306 mm is in the 8th percentile, and the eighteen month total of 659 mm is in the 6th percentile.

Climate for December 2014

The Year 2014

This year had the warmest nights (11.34°) of the new century. Although the days, at 26.67°, were cooler than in 2002 (26.72°), this year had also the warmest mean temperature: 19.01°. The second-warmest, at 18.85°, was 2009 and the coolest, at 17.19°, was 2008.
The subsoil temperature: 20.5°, fell back to near average.
In the year, 39% of the mornings were cloudy (more than four octas of cloud). This is close to the recent average (40%) for 2007 to 2014, but much more cloudy than the earlier average (26%) for 2000 to 2006.
The rainfall, 447 mm, was second lowest in the new century, after 2002 (366 mm). In the long-term rainfall record, this is a serious, but not severe deficiency: it is in the 8th percentile.


Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash  Street, Manilla.

3-year trends to December 2014

Parametric plots of smoothed climate variables at Manilla
“December 2014 rain again”

Trends to December 2014

December data (orange)

From November to December, the raw anomaly value for daily maximum temperature returned to normal from extremely high. Rainfall anomaly moved from very dry to rather wet. Most other anomalies came back to near zero, where they had been (as smoothed values) in June 2014, six months earlier.
Temperature range became low while daily minimum temperature remained high. (Which causes which?)

Fully smoothed data (red)

The latest fully-smoothed data (June 2014) mainly show a renewed movement towards drought.


Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

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.

December Climate Anomalies Log

Heat indicators log for December

This post is the tenth in a set for the 12 calendar months that began with March. Graphs are sixteen-year logs of the monthly mean anomaly values of nine climate variables for Manilla, NSW, with fitted trend lines. I have explained the method in notes at the foot of the page.

Raw anomaly values for December

Extreme values of December anomalies were as follows:

Daily Maximum Temperature Anomalies (2) -3.6 deg:
December 2010; -4.7 deg: December 2011;
Rainfall Anomalies (1) +80 mm: December 2004;
Minus (Temperature Range Anomaly) (1) +3.7 deg: December
2010;
Dew Point Anomalies (1) -4.4 deg: December 2013.

Trend lines for December

Heat Indicators

All heat indicator quartic trends began low and ended high, and had a peak in 2003 or 2004 and a trough in 2010. The range from peak to trough was greatest for maximum anomalies and least for minimum and subsoil anomalies.

Moisture indicators log for December

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