April 2021 Weather Report

 Overall cool, calm and collected dry.  The BoM declared that the La Nina event was over and so it would appear to be.

Rainfall

After a few months with well above median falls April, with 30mm, was well under the median of 79.1mm.  There are 8 Aprils (since 1975) with lower falls.

Looking at the year as a whole we are still at 125% of the average year to date fall.  This gives a prorata estimate of 1196mm for the year.  Progress on that estimate shows the impact of a couple of large events.  Note the chart starts on 9 January as good falls on 3 and 5 January give ridiculous (think tropical India amounts) estimates earlier in the year.

Temperatures

The month had a warm-hot spell from the 2nd to the 9th, after which cool became the best word.  From the 10th onwards 15 of 21 days had below average values for minimum and maximum.  The month ended with the overall average temperature 0.55C below the long term average.

The next chart compares the daily BoM temperature extremes with the average extreme values for the date.  Again clear how cool the final 3 weeks were,

A similar pattern of current daily extremes is given by my weather station.

Minimum temperatures

The average minimum temperature for the month was 11.6C, slightly. below average.  As I now have values for three years the next graph shows the monthly averages for those three years.  Tracking quite nicely.

Using my traditional presentation shows 2021 to be below 2020 and the (largely BoM) longer term average values.

Maximum temperatures

The average Maximum temperature for April recorded by BoM was 19.9C slightly below the average for that site.  As usual my weather station, not exposed to the cooing sea breeze was somewhat warmer averaging 21.3 (above the long term average (which is mainly BoM values.).  As for minimums I now have a 3 year series for my weather station which shows the value for 2021 to be right on the pattern.

The traditional graph shows an April value above long term average but below 2020,

Humidity

By Mallacoota standards humidity at my weather station was quite low, as would be expected from the low rainfall.

The average 0900 value was slightly above the value for 2020 and the historic value for the BoM.  It was the hihest of the three years for which I have WS values.

The 1500 hrs value was well below both the traditional charted values and the weather station measure in 2019.  

Wind

A calm month!  The average daily wind run was much lower than both 2020 and my historic (adjusted for exposure) BoM value.

The breezes which were recorded were heavily biased towards the West and North North West directions.  I was initially surprised at this chart, but on examining my weather station data it appears to be quite a common situation for Winter: in Summer winds from the ESE are more common.  Thus it might be held that the Winter pattern has arrrived a little early this year.