3-year trends to November 2017

Dry with cold nights

3-year trends to November 2017

November raw anomaly data (orange)

November 2017 reverted to the anomalies of August and September: low moisture (top four graphs) and cold nights (bottom left), with continuing cold subsoil (bottom right). Day temperature (x-axes)had cooled to normal since September.

 Fully smoothed data (red)

Anomaly data for autumn 2017 (MAM) are now fully-smoothed, plotted in red. That season was near the centre for the last three years, but day temperatures fell from high towards normal (seen best on the top right graph). Meanwhile, moisture measures disagreed somewhat. Rainfall rose towards normal, cloudiness decreased towards normal, dew point fell through low values, and daily temperature range was static near normal.
Daily minimum temperature fell towards normal, and subsoil temperature rose to normal.


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.


Cool Dry April 2017

Pavonia blooms on a roadside

Roadside Pavonia

April began with cool days and nights, about three degrees below normal. However, the weather did not get any cooler until the last few days. In particular, ANZAC Day, at 27.4°, was the warmest day of the month – but that was more than a degree cooler than ANZAC Day 2002. (The average daily maximum temperature for ANZAC Day (from 2000) is 24.3°. The hottest was 28.7° (2002) and the coldest 16.8° (2012).)

Soaking rain of 10.6 mm, registered on the 26th, came with a remarkably warm night of 16.6°. Coming so late in autumn, this was 7.9° above normal, breaking the record of 7.1° above normal for an April night (20/04/06).
Further rain on the 27th (11.2 mm) fell as showers on a very cold day of 14.3°, that was 9.8° below normal. The final three nights were cold. The 30th, at 4.3°, was the coldest night of the month, but it was far from frosty.

Weather log for April 2017

Comparing April months

This month was cool, with a mean temperature of 17.0°, but not nearly as cool as April in 2008 (15.8°), 2006 (16.6°), or 1999 (15.6°). It was also rather low in moisture, with only 24 mm of rain, only 33% cloudy mornings, a daily temperature range as wide as 15.6°, and an early morning dew point of only 6.3°. What is unusual is the combination of low temperature values and low moisture values. Manilla’s climate generally swings between high temperature with low moisture (“droughts”) and low temperature with high moisture (“flooding rains”), as the poet said. (See these graphs.)
The total rainfall of 24.0 mm was at the 40th percentile, below the April average of 40 mm. There are no serious shortages of rainfall for groups of months to this date.

Climate for April 2017.

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.

March 2016 had a warm dry spell

Photo of Pittosporum berries

“Native Apricots”

In the first half of March the average weekly temperature was more than three degrees above normal. Nine days had maxima above 35°, when the month usually has only one. However, no day reached 40°, as happened in March last year (20/03/15).
No rain fell in this time: the period of 43 days between February 4 and March 19 may have been the seventh longest rain-free period in 133 years. (No official record is now kept.)
Normal weather returned in the second half of the month. I recorded 20.8 mm of rain on the 19th, and further rain on the 30th and 31st.

Weather log for March 2016

Comparing March months

Despite the cool change, this was the warmest March of the new century. Daily maxima, minima, and means were all 2° above average. The subsoil temperature was also 1° high, as in March 2012 and 2013, but not as high as in 2007 (2° high).
This was not a dry month. The moisture indicators cloudiness, humidity, and (low) daily temperature range were just slightly on the dry side.
The total rainfall of 35mm was below the average of 53 mm, but in the 46th percentile, not far below the median. Again, there are no serious rainfall shortages for totals for any number of months. In fact, the five-month total of 362 mm is high, in the 81st percentile. Ponds persist in Greenhatch Creek.

Climate graph for March 2016.

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.

February 2016: hot, dry days

Photo of cooba blossom

Cooba in February

Weekly average temperatures began 2 or 3 degrees low, but ended with a long warm spell 3 degrees high, that extended into March. Days were especially hot, with the 26th reaching 41.5°, the equal second hottest February day. Nights were seldom very warm, and the early morning of the 26th was 25° cooler than the afternoon.
Few days were cloudy, none of them late in the month
Rain fell only on the 3rd, as three heavy showers of 7mm, 27mm and 13mm. The second shower, at 5pm, had the most intense rain of the new century: 27 mm in less than 27 minutes. Bureau of Meteorology data show that such a half-hour storm, yielding 1 mm of rain per minute, has only a 10% chance of happening here in any year. It is a “one in 10 year event”.

Weather log February 2016

Comparing February months

While the average temperature for the month (25.8°) was normal, the mean daily maximum, at 34.7°, was the hottest for February. A rather low mean daily minimum, (16.8°) made the daily temperature range a desert-like 17.9°. This is the widest February value, 3.5° wider than normal.
Other signs of dryness were the low early morning dew point (10.8°) and very few cloudy mornings (17%).
The total rainfall of 47mm was below the average of 67 mm, but right on the median 50th percentile: just half of all February months have been wetter. Again, there are no serious rainfall shortages for totals for any number of months.

Climate for February 2016

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.

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.

Dry July 2014

The daily weather log

Photo of sunlit house interior

July sun heats the house

Normal sunny July weather was broken by two rainy days in mid-month and another “rainy” day later. With the first rain there was a very warm night of 11.0°, at the time when nights are usually at their coldest (1.8°).
Late in the month days and nights were two degrees warmer than usual.Weather log July 2014

 Comparing July months

Average temperatures were normal, but the rainfall was low and the humidity (Dew Point) was very low. Recent July months have been quite different. Last July was very warm, July 2012 was very wet (ninth wettest), and July 2010 was very cloudy and wet, with warm nights. This month was not as dry as July 2011, which was not as dry as July in the drought year: 2002.
The total rainfall of 11.4 mm is in the 15th percentile. Taking rainfall totals for more than one month, the 4-month total of 83 mm is now a serious shortage (6th percentile). There are also serious shortages in the totals for 12 months (6th percentile), 15 months (8th percentile), and 18 months (9th percentile), Other totals have higher percentile values, and most totals for 36 months or more are above normal. In the very long term, the 30-year rainfall total (19,314 mm) has just fallen below the median for the first time since August 2010.
(Note. Figures for 30-year totals begin in 1914. The lowest 30-year total rainfall was 18,026 mm (601 mm per year) in November 1940; the highest was 21,031 mm (701 mm per year) in December 1978.)Climate July 2014

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