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.

September 2015 cold and dry

Photo of native clematis

Native clematis

Few days or nights in September were warmer than normal. The 23rd was a very cold day (17.1°) and the 24th had a very cold morning (-0.1°). The weekly temperature was near normal in the third week, but it had been cool in the first. It was cold (4.7 below normal) in the fourth week, and was rising through normal at the month’s end.
As is usual in September, most days were fine, and they were much warmer than the nights. The afternoon humidity was low (24%), but not nearly as low as in 2013 (15%).
Rain fell on only four days, with the highest reading 8.6 mm on the 4th.

Weather log for September 2015

 Comparing September months

In a dramatic change from August, both days and nights were very cold, as they were in September 2004.
The aridity was not quite as bad as in 2013, when the dew point was lower and there was less cloud.
Such cold, dry conditions are not those of an El Niño event (hot and dry) or of a La Niña event (cold and wet). If more extreme, they would be those of a glacial period.
The rainfall of 15.9 mm was well below average, in the 22nd percentile. There are still no serious shortages in rainfall totals for small numbers of months. A severe shortage (4th percentile) has appeared in the 30 month total (1186 mm). There are still deep ponds in Greenhatch Creek.

Climate for September 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 September 2015

Parametric plots of smoothed climate variables at Manilla
“September 2015: cold and dry”

Trends to September 2015

 

September raw anomaly data (orange)

September brought big changes in all raw values of climate anomalies, except for daily temperature range, which stayed rather low.
There was a sharp drop in temperatures: maximum, minimum and subsoil.
Moisture measures – rainfall, cloud and dew point – all fell.

These transitory values are unlike either the hot arid values of El Niño conditions in eastern Australia or the cold moist La Niña conditions. They are like a mild form of the cold arid conditions that are thought to have occurred in glacial periods.

 Fully smoothed data (red)

Fully-smoothed anomaly values for March 2015 continued the trends of late summer. Most moved further away from drought. Daily minimum temperature became static, and subsoil temperature began to rise.


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.

Winter 2015 like winter 2014

A low-level lenticular cloud

Low Level Lennie

Weather log for winter 2014There was one short spell of rather cold days in mid-July this year, and another at the very end of August.
Otherwise, this winter was very like the winter before. In mid-June and late August there were humid spells with heavy rain and very warm nights. By contrast, early August had cold nights with very low humidity and no rain. In both years, July had very light falls of rain.
The number of frosts in each season (38; 42) was near normal (44), but in this winter the coldest night (minus 2.1°) was the warmest so far this century.

Weather log for winter 2015

Like last winter, the average night temperature and the cloudiness were a little high, and the dew point very low. Average day temperature was half a degree low, making the daily temperature range narrow.
The winter rainfall, 133 mm, was just above the average (125 mm) and in the 62nd percentile.

Climate for winter 2015


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