Manilla’s Frosts to 2014

Graphical log of frosts

This post updates a similar one by including three more years to make a total of sixteen.

The Number of Frosts in Each Year

The first graph is a log of the number of frosts in each year. The pattern is different when counting all frosts or only severe frosts.
The log for all frosts had two periods of stable, medium numbers of frosts: from 1999 to 2003, and from 2008 to 2011. Three years had many frosts: 2004 (68), 2006 (70), and 2012 (69). The year 2007 had the fewest frosts (43) until beaten by 2013 (34).
In the logs for severe frosts below minus 2° or minus 4° in the thermometer screen, the drought year 2002 stands out as the most frosty by far. It had the coldest mornings: -5.1° on both the 2nd and 11th of July.

The Last Three Years

Monthly frosts in 2012, 2013, and 2014.

The second graph compares the mean seasonal pattern of frosts with the patterns for the three latest years: 2012, 2013, and 2014.
The frost season of 2012, which almost matched the record 70 frosts of 2006, began early and ended late. May had 13 frosts (like the 14 of 2006) and September had 10 (like the 8 of 2003).
The curve for the season of 2013 ( the new record fewest) was like that of a normal frost season, but lower.
The year 2014 was not very frosty, because the season began late, with no frosts in May and only nine in June.

Monthly frosts each year

Graphs showing the seasonal frost patterns for earlier years are copied here.

 

 

 

 

 

 


There is 2013 reserch on frost in NSW titled “Understanding frost risk in a variable and changing climate” reported here.
It is in GRDC Update Papers (Grains Research and development Corporation). The research is done by Steven Crimp and co-workers at CSIRO Climate Adaption Flagship.
Referring to the period 1960 to 2010,
“Over many parts of NSW the frost season length has broadened by as much as 40 days and the mean number of consecutive frost days has increased to 5 days.”

Manilla’s Frosts

I have a 13 year record that shows how frosty Manilla is, and how some years are frostier than others. My thermometer is on high ground, so people living where cold air collects will have had more frosts. However, my readings show changes from one time to another. As I do not have a thermometer in the grass, I have recorded a frost when my screen reading is below +2.2°.

There is a matching post for Manilla’s hot days.

Total frosts

The first graph shows the number of frosty mornings in each year. The most frosts were in the years 2004 (68) and 2006 (70); the fewest were in the years 2007 (43) and 2010 (44). The 13-year average is 54.
The graph also shows the number of mornings colder than zero, minus two, and minus four degrees. On the average, these occurred on 26, 7, and 1 mornings per year. For those colder than zero degrees, 2006 was again the frostiest, but 2002 was also very frosty. Counting only the most severe frosts (below minus two or minus four degrees) 2002 was the frostiest year. It had the coldest mornings: -5.1° on both the 2nd and 11th of July.Frosts each year, and seasonal distribution.

Frosty months

The second graph shows how most frosts come in the winter months, especially July, with some frosts in autumn, but few in spring and none in summer. Few come before Anzac Day (25th April) or after Labour Day (first Monday in October in NSW).


The graphs below show that each year was different. The drought year 2002 had the highest number of frosts in a single month: 27 in July – half of all frosts in that year. By contrast, the 70 frosts of 2006 were spread through the months of winter and autumn: there were more frosts in June and August than in July. Continue reading