Warm Nights in Summer 2009-10

 

Weather log summer 2009-10

No warm spell this summer matched that of late November, which had four days over 40°. There was only one 40° day all summer. By February there were no warm spells.
Summer began hot and very dry, with clear skies and low humidity. Year’s end saw days of rain, low cloud and extremely high humidity. In mid-January the air was again very dry, but cool.


The mean daily maximum temperature was normal, but the mean minimum (18.7°) was the highest in eleven summers. The number of nights warmer than 20° (34) is also the highest, nearly twice the usual number.
The total rainfall of 190 mm is below the long-term summer average of 225 mm. It is in the 42nd percentile.
At 42% cloudy mornings, this summer was very cloudy, but not extremely cloudy like the summer of 2007-08 (53%). These summers shared the record for completely overcast mornings, with 18 each.

Climate for summer 2009-10

 

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.

Normal Climate in Summer 2008-09

 

Weather log summer 2008-09

For most of the summer, 7-day average temperatures got steadily warmer. From 4° below normal in mid-December they rose to 4° above normal in early February. They then crashed to 5° below normal before recovering. Two days exceeded 40°: February 6th (40.1°) and February 9th (40.9°). In ten summers, 19 days have exceeded 40°, the hottest being 42.0° on 21/2/04.
This season had the coldest summer day so far this century: February 14th 2009, with 17.8°. That is 15.3° below normal (it would be normal in winter, not summer)!

NOTE. This is the daily maximum reading that is furthest below normal in the ten-year record from March 1999. There have been only 23 days when the maximum was more than 10° below normal. Only 18 days were more than 8° above normal. The furthest above normal (by 10.5°) was the reading of 38.8° on November 10th 2002.

Humidity was low both in the early cool spell and in the later hot spell. At both times the daily range of temperature was high (17°) and the skies mainly clear.
There were 23 rain days, which is normal and far fewer than the 33 rain days last summer. Dry spells (with falls less than 1 mm) were long: 21 days from the 30th of December, and 16 days from the 25th of January. February the 15th was the wettest day, with 51.2 mm, and the summer total was 228 mm.
The number of overcast mornings (12) was normal for summer, but the number of cloud-free mornings (17) was very low, as it was last summer (13).


All mean temperatures (daily maximum, mean, and minimum) were normal this summer. They were much higher than last summer, with the daily maximum a remarkable 2.8° higher. The mean morning Dew Point was also normal.

The total rainfall of 228 mm is very close to the long-term summer average of 227 mm. It is on the 54th percentile.
At 38% cloudy mornings, this summer was cloudy, but not extremely cloudy like last summer (53%).
The summers of 05-06 and 07-08 were both very wet (319 mm and 311 mm). They differed in other ways: summer 05-06 was hot, humid and not cloudy; summer 07-08 was cold, not humid, and extremely cloudy.

Climate for summer 2008-09

 

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

Summer 2007-08 was very cool,cloudy and wet

Weather log summer 2007-08

The daily weather log

Most summers recently have had one or two days over 40° and nights over 25°. Not this summer! The hottest day reached only 36.3°, and the warmest night 22.1°. Only 37 days went over 30°: half the usual number. Air conditioners may not have had much use!
The 7-day temperature curves show warm spells in the second week of December, and in the second and fourth weeks of January. Temperatures were then normal. The rest of the time they were well below normal.
Daily minimum temperatures were not so low. This made the daily temperature range small, especially during humid spells.
Humid weather (dew point 16°) came with rain in early December, mid-January, and early February. The air was rather dry (dew point 10°) at New Year and in the very last days of summer.
There were 33 rain days (normally 21). The longest dry spells were eight days from the 22nd of January, and nine days from the 20th of February. February the 6th was the wettest day, with 32 mm, and the summer total was high, at 311 mm.
It was a very cloudy summer. More than half the mornings were cloudy (over 4 octas) and many (18) were completely overcast. Only 13 mornings had a sky clear of cloud.

Comparing summer seasons

Mean daily maximum temperature and mean temperature this summer were the lowest in the nine year record. Mean daily minimum temperature was lower in 1999-2000, which has the next coolest mean temperature. While the cool summer of 1999-2000 had a large daily temperature range (15.6°) related to low rainfall, this summer had a very small daily temperature range (13.2°) related to high rainfall and cloud.
The mean daily maximum this summer (29.7°) is 3.3° below the nine-year average. The fall of over 4° from the very high maxima of the last two summers is dramatic.
Humidity was normal for the time of year.
For rainfall, this short record begins with the 15th driest summer (99-00, 125 mm) and includes the 19th wettest summer (05-06, 319 mm). This summer’s rainfall of 311 mm is 84 mm above the long-term summer average of 227 mm. It is on the 83rd percentile.
At 53% cloudy mornings, this summer season is by far the cloudiest of any season in the nine-year record. No others exceeded 41%.

Climate for summer 2007-08

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