September 2017 even more arid

Trellised vine photo

Blooming Wonga-Wonga Vines

Despite more cloud, September was even more arid than August. Weekly temperatures remained normal until the last week, which was remarkably warm. There were some notable events. The 13th, the first 30°-day of the season, was followed by a day more than 16° cooler. Extremely low humidity early on the 20th made the dew point (-8.8°) almost as low as the record set last month. Among minimum overnight temperatures that were near zero, the one on the 24th (22.8°) set a record by being 14.7° higher than normal.
The number of frosts (below +2.2° in the screen) was 13 (a September record), almost as many as in August. Perhaps the frost on the 20th was the last of the season. That is the normal date for it.
There was 5.2 mm of rain on the 14th, and an estimated 0.3 mm on the 29th. (The automatic gauge at the Museum was down by then.)

Weather log

Comparing September months

The mean daily maximum of 25.0° was rather high, fully 5° higher than last year. With a mean daily minimum (5.7°) that was rather low, the daily temperature range reached the record wide value of 19.3°.
Extremely dry air was shown by a mean early-morning dew point of 2.7°, the lowest September value, 8.1° below normal.
The total rainfall of 5.5 mm (estimated) was very far below the September average (41 mm), at the 8th percentile. That is a serious rainfall shortage. The current rainfall totals for four months (95 mm) and for six months (175 mm) are also serious rainfall shortages. Even worse are the totals for two months (19 mm) and for three months (33 mm): they are severe rainfall shortages.
Similar severe shortages occurred in October 2013, May 2008, and May 2005. Extreme shortages last occurred in the six-month drought of 2002.

Climate graph for September


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 gauge last reported on 24 September 2017.

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

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3-year trends to September 2017

More arid

3-year climate trends to September 2017

September raw anomaly data (orange)

In September 2017 all moisture indicators except cloudiness showed even greater aridity (high up on the graphs) than in August. Daily maximum temperature anomaly (x-axis in all graphs) had now risen very high, but that of the subsoil (lower right graph) had fallen. Daily minimum temperature anomaly (lower left graph) remained extremely low.

 Fully smoothed data (red)

The latest fully-smoothed data point is that for March 2017.
At that time, the climate was warm and almost static, after a minor peak in aridity. Although later anomaly values (only partially smoothed) are subject to noise, three of them have raced away towards aridity: dew point fell, daily temperature range rose, and daily minimum temperature fell.


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 2017 arid and sunny

Photo of a honey-eater feeding

Noisy Miner in Emu Bush

Very few days in August were cloudy, and only one day, the 4th, had some rain: 13.6 mm. Extremely dry air produced a 21st-century record low dew point of minus 10.0 degrees on the 20th. The dry air and clear skies dried out the soil, and also made for wide ranges of temperature. Twelve days were more than 20° warmer than their nights. The actual temperatures, however, were not extreme. Weekly average temperatures remained normal until falling to 3.3° lower in the final days.
Frosts (below +2.2° in the screen) happened on 17 mornings, just two more than normal.

Weather log

Comparing August months

Arid August months like this occurred in 2012 and 2013, but not since then. The mean early morning dew points in 2012 (-2.2°) and this time (-2.8°) were record values, far below the normal value of +2.2°. This month was also very sunny, had little rain, and had a daily temperature range of 17.9°, a record for August.
Temperatures were close to normal. The daily maximum (19.8°) was a degree above normal, and the daily minimum (1.9°) was a degree below normal.
The total rainfall of 13.8 mm (20th percentile) was far below the August average (40 mm). Added to the low total for July (13.2 mm), the two-month total is only 27.0 mm, which is at the 6th percentile. That makes it the first serious rainfall shortage of any duration since October 2015, when the 30-month total had been at the 6th percentile. For two-month rainfall totals, there has not been such a shortage since nearly four years ago (September 2013).

Climate graph for August


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

November 2016 was arid

While there was some rain, measures of moisture this month were at or near their lowest November values for this century.

Photo of a yellow dragon lizard

Eastern Bearded Dragon

There were five rain days early in the month, the highest reading being 15.0 mm on the 10th. Some early days were overcast, but skies were sunny after the 15th.
Temperatures rose and fell, but few days or nights were especially hot or cold. The early morning of the 6th went as low as 5.4° , which is 7.8° below normal. Curiously, the month had a record number of cool nights: 12 nights were cooler than 10°, when there are usually only about 5.
Weekly average temperatures, which had been very low in October, were nearer to normal through this month.

Weather log November 2016

Comparing November months

Both the mean maximum temperature (30.2°) and the mean average temperature (20.9°) were near normal, but the mean minimum temperature (11.7°) was very low. On this record, only 1999 had colder November nights (at 11.6°!). This extreme value brought a very wide mean daily temperature range of 18.5°, also a record.
The subsoil was at its coolest recorded November value: 19.5°.
A very wide daily temperature range is one of the measures of moisture showing this month to be arid. The early morning dew point of 5.6° was the lowest November value on this record, and the cloudiness (30%) was low. The monthly rainfall total of 21.9 mm, while not really low (22nd percentile), was the lowest November total in the 26 years since 1990, which had only 15 mm.

Climate for November 2016


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.

Summer 2014-15 on average

Wildflower photo

Commelina cyanea in Monash Street

This summer, January was no warmer than December or February, and none of these months was as warm as November! The number of hot days (over 35°) had a similar pattern that “sagged” in midsummer: Oct: 4 days; Nov: 10 days; Dec: 7 days; Jan: 2 days; Feb: 3 days; Mar: 2 days (in the first week). There were no very hot days over 40° this summer, although there had been three in spring.

A very cool spell from late January to early February had day and night temperatures 4.5° degrees lower than normal. Humidity was also low at that time and earlier, in mid-December.

Weather log for summer 2014-15

By most measures, this was a normal summer. Compared with the 21st century average, the daily maximum temperature and the daily temperature range were both just one degree low, and skies were a little more cloudy. The dew point (humidity) was low, but much higher than last summer.

The rainfall of 224 mm could hardly be more “normal”. It lies between the 125-year average of 227 mm and the 125-year median value of 221 mm. Summer rainfall totals like this also occurred in 2002-03 (227 mm) and 2008-09 (229 mm). Historically, summer rainfall totals in the “normal” range from 220 mm to 230 mm occurred in 1902-03, 1917-18, 1936-37, 1948-49, and 1957-58.

Climate for summer 2014-15.


Data. Rainfall data is from Manilla Post Office, courtesy of the Post-master, Phil Pinch. I thank Phil for his help over the years. When he retires this March, there is some uncertainty about the future of rainfall observations that have been maintained for 132 years since March 1883.

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

Spring 2014 dry and hotter

Weather log for spring 2014

Warm weather developed in early October, followed by a cool spell with one rain day of 26.4 mm. After that came three hot spells. There were showers and storms in the district, but little more rain fell at Manilla.
This spring was slightly hotter than spring 2013 and spring 2009, but not as hot as spring 2002. The air was not as extremely arid (dew point 3.6°) as in last spring (dew point 2.3°), and skies were a little more cloudy.
The total rainfall of 69.8 mm was in the 8th percentile: the 10th lowest spring rainfall. (Spring 2002 had been equal 5th lowest at 66 mm, and spring 1957 the lowest at 23 mm.) Rain fell on 11 days: more than in spring of 2002 (9 days), but fewer than in 2013 (13).

Climate for spring 2014


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

Winter 2014 normal

Berries on a melia tree

Chinaberries in winter

This winter, there were no very warm or very cold spells. There was one sunny spell with a wide daily temperature range in early August, followed by a week with a narrow temperature range.
There were 38 frosts. While this is below the 16-year winter average of 44, it is near the average for the last seven winters. From 2001 to 2006 the winter average was higher: 47 frosts.
Rain fell on 15 days (normal), with a highest reading of 26.6 mm, which is also normal in winter.Weather log for winter 2014

Seasonal means and totals were all not far from normal except for the dew point. The dew point of 0.7 degrees was more than two degrees low, showing extremely dry air, as in winter 2012. The daily minimum temperature was almost a degree high, reducing the temperature range and raising the mean temperature as well.

The winter rainfall total of 106 mm is just below the average (125 mm) and in the 40th percentile.

Climate for winter 2014


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