Dry August 2019

Blossoms on a street tree

August Blossoms

Weekly average temperatures steadily increased as is usual in August. Day and night temperatures also were not far from normal. The warmest day reached 27.1° and the coldest night -1.4°. There were 15 frosts, the usual number.
Rain was recorded at the Manilla Museum on the 1st (1.0 mm) and the 12th (4.6 mm).

Weather log august 2019

Comparing August months

This dry month was very like August 2013, with the August months between being mainly rather cooler and wetter.
The mean maximum temperature (20.9°) was above normal by 1.4°, and the mean minimum temperature (3.3°) was near normal. The resulting temperature range (17.6°) was high, agreeing with the rather low cloudiness (26%) and dew point (-1.0°).
The rainfall total of 5.6 mm is at the 8th percentile for July.

Climate for August 2019


I have reported separately on the on-going drought that continues to break low-rainfall records at durations of 15-months and longer.

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.  No 9 am readings were recorded from August 2018 to 19 July 2019. Recording resumed on 20 July 2019.
My estimates of early morning dew point have drifted anomalously low. From August 2019, I use data from the Tamworth Airport published graphs.
All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to January 2018

Hot and dry

3-year trends to January 2018

January raw anomaly data (orange)

January 2018, like December, had hot days and hot nights, but had even lower rainfall.

 Fully smoothed data (red)

The latest fully-smoothed data point is for July 2017.
Most variables were normal and static at that time. Dew point was low and falling, while daily temperature range was rather high and rising.


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.

Autumn 2008 was dry and cool

Weather log autumn 2008

The daily weather log

Temperatures were about normal in mid-March and again during parts of May. Otherwise they were low. The daily temperature range was generally higher than usual, but was less on rainy days.
There were nine mild frosts, which is near the average.
Humidity was very low in early April and early May.
There were 13 rain days, which is normal. They were mainly in late April and mid-May, for a very low total of 37 mm. April the 24th was the wettest day, with 12.8 mm.
Cloud varied a lot from day to day. Clear skies were common in March.

Comparing autumn seasons

This autumn was very cool: mean daily mean temperature and minimum temperature are the lowest in the ten year record. Mean daily maximum temperature was lower in 2003, which is one of three autumns sharing the next coolest mean temperature.
This autumn’s very cool nights (8.2°) caused the largest daily temperature range on the graph (16.9°), similar to the 16.8° of 2005. Both came with very low rainfall,
Autumn humidity seems to have decreased through the decade, with this autumn’s Dew Point of 6.4° the lowest.
This graph includes some very dry autumns. Autumn 2005 was the 7th driest on record, in the 6th percentile for autumn rainfall. This autumn was similar, in the 7th percentile. Autumn 2002 was in the 18th percentile, as that year’s drought had not fully developed. By contrast, autumn 2003 and 2007 were wet, in the 72nd and 75th percentiles.
(Contrary to the forecast, this autumn was dry. It was one of twelve autumns on record that had less than one fifth of the preceding summer’s rainfall. Three of the twelve were 2005, 2006, and 2008. This is amazing: something that usually happens one year in ten happened three years in four! Another three of the twelve were 1971, 1973, and 1976. At that time it was three years in six.)
At 26% cloudy mornings, this autumn was normal.

Climate autumn 2008

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Dew Point values before August 2005 are from Tamworth Airport 6 am data supplied by the Bureau of Meteorology. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash Street, Manilla.

Dry, Dry March 2008

The daily weather log

Weather log March 2008

After 115.6 mm of rain in February, March crashed to just 2.2 mm with only three rain days. In 1971 it was worse: that year February had 173 mm and March 1 mm!
This month the air was very dry, too. Morning Dew Points which had been quite low (10°) all month, plunged to zero or less in the last days.
Although there were six cloudy mornings, eighteen mornings were completely cloud-free. The whole of the summer had only thirteen free of cloud!
Due to the dry, fine weather, three-quarters of the days had a range of temperature higher than the normal value of 15.4°. Three days had a range of 21° or more.
The 7-day average temperature began and ended well below normal, but was above normal in the third week. Nights were cold (8° below normal) in the first and last days.

 Comparing March months

Climate March 2008

The mean daily maximum temperature this March (29.9°) is normal, but the mean daily minimum (12.2°) is the lowest in ten years. It is 2° below the average, and 4° below that of 2007 (and 2000).
The mean morning Dew Point, 8.8°, is 3° lower than normal for March. This shows very dry air, which is wilting many shallow-rooted plants.
The total rainfall of 2.2 mm is much lower than the other Marches on the graph. It is not very low compared with Marches in the long-term record: it is on the 6th percentile. In Manilla, rainfall varies more in March and April than in other months.
There must be a lot of water deep in the soil. Total rainfalls for the last 2, 3… 18 months are all above the median. The four and five-month totals are particularly high, in the 83rd percentile.

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Dew point values before August 2005 are from Tamworth Airport 6 am data supplied by the Bureau of Meteorology. Temperature and other data are from 3 Monash Street, Manilla.