Hard Winter for Solar-passive

Graphical log of daily indoor and outdoor temperatures for winter 2016.

Temperature log: main features

This graph, for 2016, shows a winter pattern of indoor and outdoor temperatures that is typical for this house. Indoor temperatures vary much less than outdoor temperatures, they rise and fall with them, and they are higher nearly all the time.
While the outdoor temperatures shown go as low as minus three degrees, those indoors lie within the winter “comfort zone” from 17° to 24° (see this post) nearly all the time.

Weather this winter

This winter was harsh for a solar-passive house. Near-record rainfall (227 mm) came with the greatest number of cloudy days of any winter in the new century. There were 53 mornings with more than four octas of cloud, when the average is 33.

Heater use

Because cloud limited the the solar gain, I had to use blower heaters far more than in previous winters. My records show that I used 320 kWh ($80) in these heaters this winter, when I normally use about 40 kWh ($10).
Heaters were also used by guests who were present on the six days shown. As well as being unused to the climate, the guests lived in the colder west wing of the house. They may have used 72 kWh ($18). Those guests have kindly written reviews of their visit.
Even using 400 kWh of electricity for personal heating in a winter could not make a detectable change in house temperature. I have found that blower heaters are surprisingly good at making a room in this house comfortable. As the radiant temperature of the walls is only 2° or 3° too low for comfort, it can be compensated by making the air temperature only slightly higher.

The pattern in detail

While cloudy days are not plotted here (Cloud observations for this winter are plotted elsewhere.), cloudy days can be recognised on the graph. In this climate, days with low maximum temperature and high minimum temperature are always due to cloud. Only in fine weather are days warm and nights frosty. The graph shows how the weather goes through a cycle every week or two: sunny days get warmer, then rain sets in. As it clears, the air gets even colder, before warming up again.
Indoor temperatures follow the same cycle, but there are differences. There may be a delay of up to a day, and sometimes longer.


I did scatter plots comparing all the variables shown in the first graph and I fitted linear regressions. I present the four scatter-plots that had the highest coefficients of determination (“R-squared”). Continue reading

July 2016 had a record warm night

Photo of a pond at sunset

A neighbour’s dam

The second cloudiest month of this century brought the warmest July night.
There were two very warm spells in the trace of weekly average temperature. Both were due mainly to warm nights. The second spell, coming in the third week, reached nearly six degrees above normal. On the morning of Saturday the 23rd, the minimum reading on the screen thermometer, 14.4°, was the highest July minimum in the record from 1999.
Up to the 25th, the weather was changeable, with some days overcast and rainy, and others fine and sunny. A very warm sunny day on the 17th, following a frost, had the unusually wide daily temperature range of 21.9°. From the 25th, the weather settled to what is normal for July. In the whole month, there were sixteen frosts, which is normal.
The highest rainfall reading was only 11.4 mm. Ten days had rainfall recorded, but three of these had 0.2 mm, on days when rain was not seen.

Weather log for July 2016

Comparing July months

The mean daily maximum temperature (16.9°) was normal. The mean daily minimum temperature (4.0°) was two degrees above normal, making the average temperature (10.5°) one degree above normal. Similarly, the subsoil temperature (14.7°) was one degree above normal.
The daily temperature range, normally 15.0°, was 12.9°, not quite as narrow as in 2010 (12.3°). The early morning dew point was normal. At 2.2°, it was so close the the daily minimum temperature (4.0°) that fogs were to be expected.
The month was extraordinarily cloudy. Cloud cover is assessed by the number of octas (eighths) of the sky seen to be covered by cloud at 9 am. I compare cloudiness of months by the percentage of “cloudy mornings”: those when I see more than four octas of cloud. This month, with 21 cloudy mornings, had 68%. July normally has only 35%. The only month in this century with a higher value was June 2013, with 73%.
The monthly rainfall total of 32.4 mm is below the average (41 mm), in the 47th percentile. The greatest rainfall “shortage” is now in the 48-month total (2221 mm) which is in the 14th percentile. Both Greenhatch Creek and Rushes Creek are just flowing.

Climate for July 2016.

Data. Rainfall figures for this month are from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

June 2016: extreme rain

Photo of Namoi River in high flow

Namoi River Fresh

This was the fifth wettest June in history, and had the second coldest day in this century.
Average temperatures were several degrees high until the last week, when they fell to three degrees low. In times of cloud and rain, cold days followed warm nights; at other times warm sunny days followed cold nights. There was one extremely warm night and one extremely cold day. The night before the 19th did not get cooler than 12.8°, making it the 5th warmest June night in this century. On the 27th the maximum temperature was only 8.5°: the second coldest day in this record from 1999. People remember the Friday before Queen’s Birthday in 2007 being bitterly cold, but that day reached 8.8°. The 20th of that month was the coldest, reaching only 8.3°.
This month, there were 8 frosts (usually 13) the coldest night being -1.8° in the screen.
Rain fell on 17 days, one day short of the record number here in any month (18 in June 1950!). [Note: Later, March 2017 also had 17 rain days.] The highest reading was 37.0 mm recorded on the 5th. As in May, the afternoon humidity was very high (seldom below 50%).

Weather log for June 2016

Comparing June months

The mean daily maximum temperature (16.4°) was very low, just not nearly as low as in June 2007 (14.3°). On the other hand, the mean daily minimum temperature (5.8°) was very high, as it was in June 2005, 2008, 2009, and 2013. The average temperature for the month (11.1°) was 0.8° above normal. Similarly, the subsoil temperature (16.8°) was 1.5° above normal.
The daily temperature range, normally 15.0°, was 10.6°, the narrowest yet seen in June, narrower than in 2007. Skies were rather cloudy, and the dew point normal.
The phenomenal rainfall of 114.8 mm was in the 97th percentile. There have been four wetter June months since 1883, but they were all before 1931. Thus, this is the wettest June in 86 years! Now, the greatest rainfall “shortage” is the 36-month total (1636 mm) which is in the 16th percentile. Greenhatch Creek is barely flowing, and a neighbour’s dam is almost full.

Climate for June 2016

Data. Rainfall figures for this month are from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

May 2016: cooling down

Photo of caterpillars in procession.

White Cedar caterpillars.

Until the last week of May, the warm weather of March and April continued. Three nights (early mornings) were more than eight degrees warmer than normal. At 16.5°, the early morning of the 1st was the second warmest for May in this century after 16.9° on 3/5/2000. The first frost (a black frost) came on the 25th, not as late as in 2014, when the first frost came on the 8th of June! (More frost information is here.)

I recorded rain on 7 days (normally 3 in May) but 4 of them had less than 2 mm. The highest reading was 13.8 mm on the 2nd. The afternoon humidity was very high (seldom below 40%) which may explain the bothersome mosquitoes.

 Weather log for May 2016

Comparing May months

The month was warm, especially at night, but not as warm as May in 2007 or 1999.
Skies were more cloudy than usual, at 45% cloudy mornings (more than 4/8 cloud). May is usually sunny, with only 24%, but both 2014 and 2015 had a record 52%
The total rainfall of 34.5 mm was near the average of 41 mm, in the 54th percentile. (Since 1998, every May rainfall except 2011 has been below average.) For the seventh month in a row, there are no serious rainfall shortages for totals for any number of months. Again, the greatest shortage is the 48-month total (2211 mm) which is now in the 14th percentile. Ponds persist in Greenhatch Creek, but a neighbour’s dam is dry.

Climate for May 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.

January 2016: moist again

Photo of Senna-bush

Jewel-box Cassia

Unlike December, this month saw varying temperatures. The week around the 7th was quite cool. The maximum on the 3rd reached only 22.3°, but worse was to come. The 15th reached only 21.1°: equal coldest January day in the new century (with 31/1/2001). It was more than 12° below normal, and that happens less than once in a year. There was also one very hot day above 40°, which is the normal number for January.
Rain fell, mainly as showers, on ten days spaced through the month. The higher readings were 28.4 mm on the 6th, 24.2 mm on the 23rd, and 27.6 mm on the 24th.

Weather log January 2016.

Comparing January months

Like January last year, this month could be called “moist”. It was cloudy, and the rather cool days were only 14° warmer than the nights.
The total rainfall of 104.7 mm was well above the average of 87 mm, and in the 72nd percentile. Again, there are no serious rainfall shortages for totals for any number of months. In fact, totals for 2-, 3-, 4-, 5-, and 6-months are very high.

El Niño

Manilla’s climate is now out of step with the El Niño – Southern Oscillation (ENSO). This “super” El Niño has not brought dryness here, and the dryness in January 2014 (for example) came at a time without an El Niño.

Climate for January 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.

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.

Cloudy autumn in 2015

Photo of eucalyptus tree

Eucalyptus albens in bloom

For a time around the 20th of April, days averaged five degrees colder than normal. At that time nights were warm, making the daily temperature range a remarkable eight degrees less than normal. On three occasions the dew point (humidity) was down by six degrees or more: early and late in March, and in mid-May. The sub-soil temperature was low most of the time by up to half a degree, but ended one degree high. Rain fell in each fortnight. The number of rain days (19) was high, but the highest daily reading (26 mm) was normal. Weather log for autumn 2015 This autumn, like the last, was moist. The rainfall, at 137.5 mm, was a little higher (on the 60th percentile) and the mean daily temperature range was a new record narrow value of only 14.0°. The season was very cloudy, with 41% cloudy mornings, but did not beat last year’s record 48%. The early morning dew point, 7.2°, was not even up to normal (8.5°). Warm nights and cool days made the mean temperature normal. Climate for autumn 2015

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