Driest Air in August 2018

Tree with a face painted on it.

Painted Box Tree

Temperatures were not far from normal during the month, except that the weekly mean was 3.2° low about the 20th. There were 20 frosts (normally 15), but the coldest morning fell only to -2.7°.
Some rain fell early in the month. Later, with the cold nights, the air became extremely dry, reaching a new record early morning dew point of -12.1°. Abruptly, the 25th brought overcast and high humidity, then rain and fog. Estimated rain was 9.0 mm on the 26th, 10.2 mm on the 27th, and 0.8 mm on the 28th.

Weather log August 2018.

Comparing August months

The month was rather cool, with a mean (10.7°) that was 0.4° below normal, and cold nights (2.0°), 1.1° below normal. Measures of moisture were only slightly low, except that humidity was extremely low, setting a new record mean early morning dew point of -4.2°.
Moderate falls of rain totalled 28.2 mm (estimated), which is at the 40th percentile for August.
I have reported the shortage of rainfall separately ( “Drought Sixth Month: August 2018”) .

Climate in August months.


Data. A Bureau of Meteorology automatic rain gauge operates in the museum yard. From 17 March 2017, 9 am daily readings are published as Manilla Museum, Station 55312.  These reports use that rainfall data when it is available.  The record was again defective in August 2018. Seven daily readings were missing. On one of the missing days (the 27th) my rain gauge showed 10.2 mm, the highest daily reading for the month. I have substituted my non-standard gauge readings for all days of both July and August.

All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to August 2018

Cooler and Moister

3-year trends to August 2018

August raw anomaly data (orange)

For now, a retreat from drought is shown by lower temperature, particularly at night, and more rain. Dew point remains very low.

 Fully smoothed data (red)

The summer season, ending in February 2018, can now be fully smoothed. February has a new 21st century record [in blue] for smoothed daily maximum temperature anomaly of +1.58° [x-axis all graphs]. This is bound to be broken by smoothed values for March, and perhaps for April. The record for negative rainfall anomaly (set in the drought of July 2002) is also likely to be broken in March.

Through the summer, all three temperatures rose, and rainfall fell. Other variables were static.


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.

3-year trends to August 2017

Arid and sunny

3-year climate trends to August 2017

August raw anomaly data (orange)

In August 2017 all moisture indicators except rainfall showed even greater aridity (high up on the graphs) than in July. Daily minimum temperature anomaly (lower left graph) fell extremely low, but both the daily maximum temperature anomaly (x-axis in all graphs) and that of subsoil (lower right graph) were just slightly above normal.

 Fully smoothed data (red)

Fully-smoothed data points now include summer 2016-17. The daily maximum temperature anomaly peaked in February 2017 at +0.9°, much the same temperature as in the previous two peaks: February 2016 and October 2014. The daily minimum temperature anomaly was just about to peak, but the subsoil temperature anomaly was rising persistently.

Moisture anomaly variables, which had moved strongly towards arid in the spring, peaked in aridity during the summer:

Lowest rainfall, in January, was just 13 mm below normal;
least cloudiness, in February, was still 11% above normal;
lowest dew point, in November, was 1.7° below normal;
widest daily temperature range, in January, was only 0.1° wider than normal.

Although aridity reached peaks, this was not an arid summer. The peak values cited were not far from normal, and the graphs show that more arid times occurred within the previous two years.


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.

Wet August 2016 had two cold days

Photo of knife-leaf wattle blooms

Knife-leaf Wattle

Six days with at least eight millimetres of rain made for a very wet August.
On the average, the temperature was normal until the fourth week, which was cool. However, there were two remarkably cold days. The 3rd, at 10.6°, was the second coldest August day and the 22nd, at 11.6°, the fifth coldest. Most nights were cool, around 1°, but several were much warmer, generally with the rain. Most days were sunny, and eighteen of the mornings were frosty, about three more than usual.

Weather log for August 2016

Comparing August months

On average, the days were cold: as cold as in August 2001, but not as cold as in 2008 or 2010. The average night-time temperature, however, was normal. The dew point, while not high, was higher than in the previous four August months.
The monthly rainfall total of 80.2 mm was twice the average (40 mm), and in the 89th percentile. No rainfall total for any number of months is now below the 19th percentile. That is the 42-month total of 1949 mm, which is a mere 313 mm lower than the median 42-month value. Both Greenhatch Creek and Rushes Creek have flowed in recent weeks.

Climate for August 2016


Data. Rainfall figures for this month are from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to August 2016

Parametric plots of smoothed climate variables at Manilla
“August 2016 cool and wet”

Trends to August 2016

August raw anomaly data (orange)

August 2016 was marked by low mean daily maximum temperature and high total rainfall. On the first graph the data point is in the cold wet “flooding rains” corner. However, the other five variables are close to normal.

 Fully smoothed data (red)

Fully-smoothed data is now available for the summer of 2015-16. Most variables became static in that season, but cloudiness increased, dew point fell, and subsoil temperature rose.
Most variables were close to normal: rainfall, cloudiness, daily temperature range and subsoil temperature. Daily maximum and minimum temperatures were rather high, while dew point was low. [Low dew point anomalies near the line (y = -x – 3) rather than (y = -x) may be due to an instrument error, since corrected.]


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.

August 2015 normal weather

Vine blossom photo

Wonga-Wonga Vine

Up to the 24th of August, there had been no rainfall readings above 6 mm for 67 days, and none at all for 29 days. Then storms brought 34 mm one day and 4 mm the next. A little more fell on the 28th. Overcast skies came with the rain, and one morning had fog until after 9 am.
Two days were unusually cool: the 5th was 6° below normal and the 27th was 7° below normal. By contrast, the minimum temperature on the warm rainy morning of the 24th (13.5°) was 9.4° above normal. There were 15 frosts (normal), but the coldest morning, the 5th, reached only minus 2.1°.
The weekly average temperature was a little low in the sunny first half of the month. It was high just before and during the rain, then low again.

Weather log for August 2015

 Comparing August months

This month was close to normal, and very like August last year.
Days were a bit cool. That made the daily temperature range rather low, in line with rather cloudy skies.
The rainfall of 40.1 mm was on average, and in the 57th percentile. As happened last month, only one rainfall total was as low as the 9th percentile. That serious shortage had now moved back to the 30-month total (1255 mm). Water is flowing in Greenhatch Creek.

Climate for August 2015


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 August 2015

Parametric plots of smoothed climate variables at Manilla
“August 2015: cooler, moister trend persists”

Trends to August 2015

Fully smoothed data (red)

The last fully-smoothed data point (February 2015) completes the summer of 2014-15. This summer had a steady cooling and moistening trend for all variables except subsoil temperature, which passed through a minimum. Three of these seven variables were very close to normal: daily maximum temperature, rainfall, and subsoil temperature. Skies were rather cloudy, dew point was three degrees low (as is now usual), daily temperature range was half a degree low, and daily minimum temperature was half a degree high. These four variables all relate to moisture. Only the dew point shows low moisture: the others show high moisture, while the rainfall was normal.

August raw anomaly data (orange)

The partially-smoothed data points from March to July (uncoloured) show excursions, but the unsmoothed data point for August (orange) is close to the trend established in the summer. That is, cooler and moister. However, no variables had values far from normal.


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.