January Weather Report

 In summary fairly damp and cool: Summer appears to be very sporadic.

Rain

The total rain recorded (73mm) was well above the median for January, but a little below 2022

On looking at these data I was intrigued to see that January has the lowest median rainfall, which is a tad hard to pick out in calendar year data, so I charted median and mean rainfall x month for a year ended 30 June.

I was further surprised to note the high mean rainfall in June and April.  This seems to be due to those months having a relatively high proportion of incidences of falls >200mm: of 28 such falls 5 are in June and 6 in April. (Why there are relatively many days of high rainfall in those months is above my pay scale.)

Non-trivial rainfall occurred on 11 days of the month, mostly as a moderate rate.  The exception was on the 3rd, when the maximum rate was 147 mm/hr.

By the end of the month my pro-rata estimate of likely annual rainfall was 1,054 mm which is (as would be expected) somewhat above average.

Temperatures

Overall the difference between the month's average temperature an the long term mean January temperature was -0.91C.  So rather cool.  Compared to previous patterns we had an excess of days with below average minima and maxima.

The daily extremes from my weather station (WS) are shown in the attached chart together with long term averages for the date.  The maximum of 16.3C on 4 January was the lowest January maximum recorded (after making adjustments to calibrate past BoM data with my WS).  Checking the BoM data for Mallacoota the 4th was very slightly above the lowest ever January maximum: either way it was cold!

Minimum temperatures

The average minimum temperature for the month was 16.34C, above average but well below the value for 2022.

The highest minimum recorded in the month was 21.3C on the 14th.  This was equal 20th ran: the all January high minimum was 24C in 2018.

The time series of average minima shows an upward trend but with so much variability from month to month the trend is not significant.

I have developed a concept of Cold Snap (the equivalent of a Heat Wave) which is three consecutive days in which both maximum and minimum are significantly below average.  There were no days which matched those criteria during this month. Three days minima were significantly below average (2 of which also had low maxima) but not 3 in a row.

Maximum temperatures

Note that the following discussion is based on a series where I have adjusted the BoM Airport data to compensate for the effect of cooling sea breezes there.  Conspiracy theorists: please enjoy.)  

To quote from the late 1960s, this month was  "Way cool, man."  Only one January (2000 with 23.1c) has a lower average maximum temperature than this one (23.46C).  I have discussed the lowest daily maximum above.  

The highest temperature recorded in the month was 31.7C on the 28th: the only day above 30C: on average there are 5 days above 30 in January with 2006 being a stinker: 12 days that hot.  The only previous month with less than 2 days over 30 was 2000 - as noted above the month with the lowest average maximum.

The time series for maxima shows how the average maximum has fallen off a cliff since 2020: I assume this is an effect of the cloudiness associated with La Nina.

Not surprisingly in view of the low average maximum there were no heat waves in this period.

Humidity

The month was noticeably humid.  As shown below the afternoon reading was very close to, or above, the morning reading on many occasions.

This led me to compare the last month with hourly humidity readings for the previous 3 Januaries (since I fired up my WS in February 2019).  The average humidity was higher in the last month for every hourly reading.

For the two standard times the last two years have been quite similar and both well above the two earlier years (and the average).

Wind

A fairly draughty period in the middle of the month followed by gradually decreasing windruns towards the end.  The longest run - 263 kms on te 14th - was the 7th longest January run (but only the the 57th longest run looking at all months. 

Windruns for January have been quite similar for the 4 years which I have record.