Autumn 2018 dry and very warm

Gum nuts and blossoms

Gumnut and Gum-Blossum

The air became four degrees warmer than normal by day and by night in mid-March and continued warm until late in April. As normal temperatures returned the climate became dry, with no rain for thirty-nine days.

Graphical weather log for autumn 2018

Both autumn 2016 and autumn 2018 had record high average temperatures. This season had the highest mean daily maximum (27.7°), but 2016 had the highest mean daily minimum (12.1°). In the combined average, 2016, with 19.9°, was warmer than 2018, with 19.7°.

All four indicators of moisture (rainfall, dew point, cloud, and daily temperature range) agree in showing this autumn to be drier than last autumn, and even than the three autumns before that.
The total rainfall of 45 mm was the 12th driest on record, but it was not the driest in the 21st century. Similarly dry autumns occurred in 2002 (60 mm), 2005 (35 mm), 2006 (53 mm), and 2008 (37 mm). That is about twice as many as history would suggest.

Climate for autumn 2018


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. During this autumn season 30 daily readings were missed, and I replaced them with my own readings.

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

April 2018 very warm and sunny

Gum tree

Schoolyard Lemon-scented Gum

Warm spells several degrees above normal persisted until late in the month. Then normal temperature returned.
While no day went over 35°, thirteen days went over 30°, which was a record. ANZAC Day, at 27.3°, was 3° warmer than usual. That was much the same as last year, but not nearly as warm as in 2002 (28.7°).
A record 25 nights were warmer than 10°. There were no frosts, the coldest night (the 29th) being 5.2°.
There were only three rain days, with the highest reading of 10.2 mm on the 20th. The number of cloudless mornings (16) was a new record, beating April 2001 (15).

Weather log for April 2018

Comparing April months

As in March, so in April, this very warm dry month matched the same month in 2016. The three highest mean temperatures for April months were: in 2018, 20.7°; in 2005, 20.6°; and in 2016, 20.5°. For mean daily maximum temperatures, however, 2005 was the warmest, at 29.5°. April 2018 claims the record highest mean minimum temperature of 12.5°, beating April 2014, which had 12.2°.
The rainfall total of 17.8 mm was at the 31st percentile, well below the average (40 mm). In 2018, rainfall has been below normal in January, March and April. However, serious rainfall shortages below the 10th percentile are still seen only in the medium term: the 60-month total of 2780 mm is at the 8th percentile, and the 72-month total of 3370 mm is at the 6th percentile.

Climate in April 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 gauge, which had last reported on 24 September 2017, came on line again on the 16th of March.

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

March 2018 very warm indeed

Acacia salicina

Young Cooba

Eight days went over 35° this March, beaten only by nine days in March 2016. The 19th (38.6°) was the fifth hottest March day of the new century. Weekly mean temperatures rose to 4.6° above normal by the 18th, and remained almost as high beyond the end of the month.
There were seven rain days, with the highest reading of 16.5 mm (est.) coming early in the month.

Weather log for March 2018

Comparing March months

Average temperatures this month very nearly match those of the record-breaking March 2016. They are only 0.1° lower! Moisture variables are also similar: rather dry, in stark contrast to the sogginess of March 2017.

The rainfall total of 25.6 mm (est.) was at the 40th percentile, well below the average (53 mm). Serious rainfall shortages are seen only in the medium term: the 60-month total of 2770 mm (8th percentile) and the 72-month total of 3410 mm (9th percentile).

Climate in March 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 gauge, which had last reported on 24 September 2017, came on line again on the 16th of March. However, not all later days have readings reported.

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

Summer 2017-18 very warm

Many cockatoos in a tree

Noisy Cockatoos

The heat waves of this summer were several degrees cooler than those of last summer. Also, unlike last summer, there were several cool spells between them. Arid spells with extremely low dew points came in mid-January and mid-February.
While last summer had 12 very hot days (over 40°), this summer had only 4; not as many as in the summers of 2013-14 (5), 2003-04 (6) or 2002-03 (5).
For most of the season, as falls of rain were light, and came at increasingly long intervals, the soil became very dry. That changed on 25 February, which had rainfall of 54 mm.

Graphical weather log for summer 2017-18

While this summer is the second-hottest of the new century in Manilla, its mean temperature (26.6°) is a degree below last summer’s 27.6°, and close to that of 2005-06 (26.3°). The subsoil temperature has been low (24.6°) in each of the last three summers. Two other measures have held steady, but a little high: cloudiness at 38%, and daily temperature range at 16°.
While the mean dew point is lower (less humid) than in last summer, the total rainfall is higher. At 140 mm (estimated), the rainfall is still well below the summer mean of 227 mm. It is at the 20th percentile, perhaps the 25th driest summer from 1883.

Climate for summer 2017-18


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. That gauge failed (again) on the 25th of September 2017, and later readings are from my non-standard gauge.

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

October 2015 very warm

Photo of native jasmine

Sweetest Jasmine

The first 30-degree day of the season came on the 3rd. That was ten days late, but the first 35-degree day followed soon after, on the 6th. Most days and nights were warm through the month, and the weekly mean temperature was three or four degrees above normal until the last week.
Ten sunny days were followed by days with much more cloud, and four rain days (usually seven). On the 22nd and 23rd, I recorded 17.4 and 8.0 mm.

Weather log for October

 Comparing October months

This was the warmest October of the new century for all daily temperatures: maximum, mean and minimum. The mean temperature of 21.7° was 3° above average, and much higher than in the other warm Octobers of 2014 (20.6°) and 2007 (20.4°).
The graph shows the curious fact that October months have warmed steadily since 2011. Since 2012, Octobers have not become drier: rainfall, cloudiness and humidity have increased rather than decreased.
The rainfall of 35.0 mm was below average, in the 29th percentile. As in last month’s report, there are no serious shortages in rainfall totals for small numbers of months. The only serious shortages are in the 30 month total (6th percentile) and in the 42 month total (7th percentile). There are still deep ponds in Greenhatch Creek.

Climate for October 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 October 2015

Parametric plots of smoothed climate variables at Manilla
“October 2015: very warm”

Trends to October 2015

October raw anomaly data (orange)

After a cool September, October was very warm: the warmest of the new century in both daily maximum and daily minimum. The daily temperature range was also high, but the soil temperature was not. Rainfall remained rather low, while cloudiness and dew point were near normal.
[The recorded anomaly values for daily maximum and for daily minimum were +3.2° and +2.2° respectively. For convenience, I have plotted them 0.2° lower.]

 Fully smoothed data (red)

In the latest fully smoothed data (April 2015) all trends on the first four graphs continued to move steadily away from drought. The daily minimum temperature anomaly began to rise, and subsoil temperature rose faster.


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.