March Weather Report

 After flirting with a call of La Nina the BoM has reverted to a suggestion of neutral conditions for the near future, based on the usual analysis of ocean temperatures.  It is, of course, daft to compare current temperatures for a small area such as Mallacoota with climate drivers for a couple of oceans and a continent, but this dry warm/hot month is far more suggestive of El Nino.

Rainfall

What is this thing called rain?  A total of 35.6 mm for the month, with one large dew collection (0,2mm) on 31 March as the only contribution since 20 March.  Not surprisingly well below median fall and March 2023.

After a few heavy falls in January there has been very little rain so my pro rata estimates for the year have declined steadily.  The current pro-rata estimate for the year is 742mm (which would be the 4th lowest on record - but there is a long way to go).

Temperatures

Definitely an interesting month.  The temperature anomaly finished at +1.18C after getting what share-market analysts would call "bullish" - peak of +2.72C  - in the middle of the month.

The time series of anomaly values seems to show this month as part of a higher plateau, while the 12 month moving average continues to show an upwards trend.

The daily extremes show a very interesting pattern.  The earlier part of the month shows a very hot period, after some people were bewailing there not having been a Summer.  That was followed by the rest of the month being much milder in moving around the long term average for the date.

The immediately following material addresses to some extent both maxima and minima, so I have included it here rather than in the subsections below.  

I have recently posted giving some standard terminology I intend to use to cover extreme temperatures which I observe.  There were quite a few occurrences meeting the required criteria in March!  

• In the weather extremes chart above it is clear that the period from March 6 to 15 had consistently above mean minimum temperatures.  In that 10 day period 7 days had a minimum more than 1 SD above the mean, with 2 days more than 2 SDs above the mean.  For the month as a whole we added 2 more days more than 1 SD above the mean.
• The extensive period of hot minima was a little longer than that for maxima, where the extremes ran from the 5th to the 12th.  In that time we had 5 days greater than 2 SD above the mean.  There was 1 further day more than 1 SD above the mean.
• So  using my standard terminology we had:
• 13 warm days
• 6 hot days
• 2 warm spells lasting 7 and 3 days
• 1 heat wave lasting 4 days.  Had the minimum on 14 March been 0.4 higher we would have had 3 consecutive days with both measures more than 2 SD above the mean which I would define as an Extreme Heat Wave.

Balancing the heat (to a very limited extent) we also had 4 cool days with minima more than 1 SD below the long term average and 1 cold day with both minimum and maximum more than 1 SD below the long term average.

Minimum temperatures

The average minimum for the month was 15.27C, 1.06C above the average since 1994.  This year March was also a little warmer than last year.

For a time series I am using a plot of monthly values since I set up my weather station (WS) in 2019.  This shows 2024 as being in the upper part of the range, but not outstandingly so.

Reviewing the history of minimum temperatures those on the 9th and 10th were the 2 highest minima recorded in Mallacoota.  The 5 warmest minima in the month (all obviously >1SD above the mean) all fall in the 50 highest March minima (of 937 non-null records).  The minima on the 5th (rank 32nd) and 22nd (ranked 30th) were in the 50 lowest March minima.

Maximum Temperatures

The average maximum for the month was 24.7C, the second highest recorded and only 0.2C below the record.  Much above average and 2023.

Again looking at the traces from my WS this year is the warmest of the six years for which I have records. 

Reviewing the history of maximum temperatures (adjusted for earlier years to allow for the effect of sea breezes on the airport maxim in earlier years) the 35.1C recorded on the 10th was the second highest in March at Mallacoota.  The 4 warmest maxima in the month (all obviously >1SD above the mean) all fall in the 50 highest March minima (of 946 non-null records).  None of the maxima in the month  were in the 50 lowest March minima (the coolest day was only the 77th lowest maximum).

Humidity

The daily chart is almost a model of consistency in terms of the morning and afternoon reading relating to each other.

The morning (0900 hours) reading is a little above the average (since 2019) but below last year.  I find this a little surprising in view of the low rain.  I have looked for a relationship with wind direction and/or temperatures but couldn't identify any explanation that way!

More in line with my expectations, the afternoon reading was below the 6 year average and the value recorded in 2023.

Wind

Overall, more windy than March 2023 but a little below the average for March.

The daily runs show 2 outstandingly drafty days.  They are 5th and 8th in rank of March windruns (but slump to 40th and 55th if all months are examined).