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.

May 2018 third driest

Sunset clouds

the heavens’ embroidered cloths

Temperatures did not stray far from normal. The first (black) frost that I observed was on the 15th, near the normal date for it (13th May). That began a week of sunny skies and very dry air.
There was only one rain day. An early morning shower gave a reading of 1.2 mm on the 30th.

May 2018 weather log

Comparing May months

The May months in 2018, 2017, and 2016, as well as in 2014, were all warm. The average temperature was more than half a degree above the normal value of 13.3°. While May 2017 was warm, wet, and humid, May 2018 was warm, dry, and arid. The air was exceptionally dry, with the mean early morning dew point (0.0°) the lowest for May, and the relative humidity at that time 68% instead of the usual 80% to 90%.
The rainfall total of 1.2 mm was third driest for May, equal with May 2002, but not as dry as May 2006 ( 0.2 mm). Only May 1927 was drier, with zero. May rainfall values have been low in the 21st century, with an average of 23 mm, compared to the long-term average of 41 mm.

Climate in May months

Rainfall Shortages

Last month, April 2018, had only two rainfall shortages classed as “serious” (below the 10th percentile): those for durations of five years and six years. Since then, more shortages have appeared. Those five-year and six-year shortages remain, but there are now serious shortages for durations of five months and twelve months, and severe shortages (below the 5th percentile) for one month, two months and three months. The current three-month total (45 mm) is at the 4th percentile.


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, during the month of May eleven daily readings were blank. I have substituted my own gauge readings, which were all zero.

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

3-year trends to May 2018

Warm and Very Dry

3-year trends to May 2018

May raw anomaly data (orange)

The raw maximum temperature anomaly for May 2018 was rather high, as was that of the subsoil. The anomaly of daily minimum temperature was low. Very low moisture was shown by the rainfall, daily temperature range, and dew point anomalies, but cloudiness was normal.

 Fully smoothed data (red)

Fully-smoothed data are now available for the spring months (SON) of 2017. In that season, all three temperatures were within their normal range. Both air temperatures were rising, but subsoil temperature was falling.
Rainfall was moving up the graph to less than normal (i.e. arid). The other three moisture measures were moving down their graphs towards humidity: cloudiness more than normal (i.e. humid), dew point still less than normal (i.e. arid), and daily temperature range still wider than normal (i.e. arid).


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.

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.

3-year trends to April 2018

Hot and sunny

3-year trends to April 2018

April raw anomaly data (orange)

Raw temperature anomaly values for April 2018 were very high for daily maxima, daily minima and subsoil. Rather low moisture was shown by the rainfall and daily temperature range anomalies, while cloudiness was very low (sunny days), but dew point was near normal.

 Fully smoothed data (red)

In the latest fully-smoothed data, for October 2017, while rainfall anomaly continued to move up its graph towards dryness, the other three moisture anomalies (cloudy days, dew point, and daily temperature range) had just begun to move down towards wetness.
For temperatures, both daily maximum anomaly and daily minimum anomaly were rising rapidly. Subsoil temperature anomaly continued the rapid fall from its peak value (normal) in June 2017.


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.

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.

3-year trends to March 2018

Hot and rather dry

3-year trends to March 2018.

March raw anomaly data (orange)

March 2018 was more like January than February. Day and night temperature anomalies were high. Moisture anomalies retreated somewhat from very low values. Subsoil temperature moved back from low to normal.

 Fully smoothed data (red)

In the latest fully-smoothed data, for September 2017, temperatures, which had been static, began to increase. On the other had, moisture anomalies, which had been moving up the graphs towards drought, became static.

Earlier, the month of February 2017 marked a sharp reversal of trend in climate anomalies. Daily maximum temperature anomaly peaked. Most anomalies (not rainfall) retraced in March and April the values of January and December. The curvature of the trace (relative to daily maximum temperature anomaly) kept the same sense after April 2107 as before December 2016. For subsoil temperature anomaly, the trend reversal came four months later, in June 2017.


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.