July 2017 fine with cold nights

July morning photo of Manilla from the lookout

Manilla Prospect in July

Through most of the month, days were fine and sunny, but some days, mainly in the middle, were cloudy and some had a little rain. The highest reading, on the 16th, was only 7.4 mm.
No days were remarkable except the 28th which, at 23.7°, equalled the record for July set 31/07/14. It was 6.1° above normal.
Frosts (below +2.2° in the screen) happened on 23 mornings, 6 more than normal. However, the coldest morning, at -2.6°, was not nearly as cold as the record of -5.1° set in 2002.

Weather log

Comparing July months

Unlike July 2016, which had been cloudy with warm nights, this July was fine with cold nights. Days, at 18.1°, were not quite as warm as in July 2013 (18.9°), the warmest in the new century.
Moisture was scarce, as in the record-making July of 2002. Readings that reflected low moisture were:

Daily minimum temperature very low: +1.2° (2002: 0.9°);
Very many frosts: 23 (2002: 27);
Very low percentage of cloudy mornings: 29% (2002: 23%);
Very low early morning dew point: -1.4° (2002: -1.4°);
Very wide daily temperature range: 16.9° (2002: 18.5°);
Very low rainfall: 13.2 mm (2002: 1.0 mm).

Relative humidity in the early mornings, normally 90% in July, was 74%. That was the lowest July value in my 13-year record.
Despite the total rainfall of 13.2 mm (16th percentile) being far below the July average (41 mm), there are still no shortages of rainfall for groups of months. The most recent serious shortage was nearly two years ago. In October 2015, the 30-month total to that date (1216 mm) was still down at the 6th percentile. That shortage was carried over from an earlier extreme event: the 85 mm summer rainfall of 2013-14 that was 142 mm below average.

Climate graph for July

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.

3-year trends to February 2016

Parametric plots of smoothed climate variables at Manilla
“February 2016: suddenly dry”

Trends to February 2016

February raw anomaly data (orange)

In February 2016, raw values for anomalies moved completely across the graphs, from cool and moist in January, generally to hot and dry in February. As in a desert, days became very hot, skies very sunny, and the daily temperature range extreme. Rainfall and dew point were only moderately low, while daily minimum temperature abruptly fell very low, and subsoil temperature remained very low.

 Fully smoothed data (red)

With data for August 2015, fully smoothed data is complete for winter 2015. Most anomalies for the season were quite small, but were moving away from cool and moist.

Trend lines on the graphs

Manilla’s climate often oscillates along the blue trend lines from bottom left (cool, moist) to top right (hot, dry) on the graphs. The climate can also vary along other axes.
In this time-frame the sub-soil temperature anomaly (bottom right graph) is leading the daily maximum temperature anomaly by several months. That produces a clockwise looping pattern. The daily minimum temperature anomaly (bottom left graph) sometimes moves with the daily maximum temperature anomaly, and sometimes moves against it. When against it, as from July 2013 to October 2014, the climate swings between Continental, with hot days and cool nights (as October 2013), and Maritime, with cool days and warm nights (as May 2014). Current raw data for January and February 2016 show a large swing from Maritime to Continental.


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.

Sunny April 2011

The daily weather logWeather log April 2011.

April weather cooled as usual, except that the second week was rather cooler, by day and by night. There were no frosts.
Most days had little cloud. There were six rain days (usually four), with the highest reading 17.4 mm on the 11th.

 Comparing April monthsClimate April 2011.

Mean temperatures were close to average. It was a very sunny month, with only 20% cloudy mornings (>4/8 cloud). April 2005 had been even sunnier, with only one cloudy morning.

The rainfall of 31.6 mm is on the 50th percentile for April: it is on the median – half of all Aprils have been wetter and half have been drier – but below the long-term average (39.3 mm). Rainfall totals for 5, 6, 9, and 12 months remain very high: above the 70th percentile.

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.


Fine cold days in July 2007

The daily weather logWeather log July 2007

Most days in July were cooler than normal. The first chart shows cold days persisted for more than a fortnight. The coldest, on the 16th, reached only 10.5°, which is 5° below normal. However, the weather was mainly pleasant, with more fine days and fewer cloudy days than usual.

There were warm nights at each end of the month, including one 7° above normal. In the middle, there were thirteen frosty nights in a row (below +2.2 degrees in the thermometer screen). The lowest temperature for the month was minus 4.4°. There were 17 frosts in total; far fewer than the 28 frosts of July 2002. (Note added in 2014: Up to, and including 2011, minima have been below minus 4° only sixteen times:  June 2000 (5), June 2002 (1), July 2002 (6), July 2003 (2) and July 2007 (2).)

With both days and nights being so cold, the weekly average temperature went as low as 4.7° below normal on the 17th.

There were seven rain days, which is normal, but the highest reading (on the 1st) was only 4.2 mm.

 Comparing July monthsClimate July 2007

This July had colder daytime maximum temperatures than any July in the last seven. Night-time minimum temperatures were also a bit on the low side. July 2002 stands out from the others. It had by far the lowest night-time temperatures in these years: three degrees below the average. Cloudiness was low in both 2002 and 2007.

The month’s rainfall of 9.0 mm is quite low, in the 12th percentile for July. However, there have been few dry months recently, so no totals for more than one month are as low as the 20th percentile.

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Dew point values before August 2005 are from Tamworth Airport 6 am data supplied by the Bureau of Meteorology. Temperature and other data are from 3 Monash Street, Manilla.