December 2007 cool, humid, cloudy, rainy

The daily weather logWeather log December 2007

Only four days, early in the month, had daily maximum temperatures warmer than normal. Decembers average five days over 35°, but there were none this month. The 22nd was nine degrees cooler than normal, at 24.2°. Daily minimum temperatures varied around the normal values (16°). The 7-day daily average temperature stayed below normal most of the time.

The graphs include the humidity of the air, using the Dew Point idea. All air contains moisture. If it cools to its Dew Point temperature, it gets so moist that cloud or fog forms, and dew appears. On humid days when the Dew Point is above 17°, most people find the weather unpleasantly sultry or sweaty. They find air with a low Dew Point, such as 5° or 10°, very pleasant and refreshing. The Dew Points shown on this graph are the early morning minimum values. Morning Dew Points this December were often between 15° and 18°: too humid for comfort. They never came below 10°.
Many mornings this month were overcast, and there were never two fine mornings together until the 29th.
There were fourteen rain days, with a total rainfall of 129.4 mm. The wettest day was the 4th, with 25.2 mm. There were only two runs of four days without rain, beginning on the 18th and 28th.

 Comparing December monthsClimate December 2007

The average daily maximum temperature this month, 29.4°, was far below the average for the last nine Decembers (31.7°). Only December 1999 had a slightly lower value (29.2°). The daily mean temperature (23.0°) was below average (24.0°), and the daily minimum temperature (16.6°) was near average (16.4°). As a result, the daily temperature range this month was only 12.8°.

The mean morning Dew Point for December 2007 is 14.2°. This high value, (meaning high humidity) seems to be about 2° above normal, but my record is short.
This was one of the three cloudiest months in nine years. The other two were also in 2007: November (50%) and June (60%).
The rainfall total of 129 mm makes this a very wet month. Only 14 Decembers since 1884 were wetter.
The year 2007 was wet: the total rainfall amounted to 741 mm. This is on the 68th percentile, meaning that higher rainfall has occurred roughly one year in three. The rainfall was 90 mm above the average (651 mm). It was the highest total since the strange wet year of 1998 (919 mm). That year nearly 400 mm more rain than usual fell in the six months that are normally the driest: from April to September.


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.

 

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