Monthly Weather Review, September 2023
October 1, 2023
Summary
The total rainfall was 4.4 mm. This is 13.1% of the long-term September mean.
The mean maximum temperature was 20.9° C. This is 2.9° C warmer than the long-term September mean.
The mean minimum temperature was 8.4° C. This is 0.4° C warmer than the long-term September mean.
Weather Records
The total rainfall of 4.4 mm is the lowest September rainfall. The previous record was 9.7 mm in 2018.
The mean maximum temperature of 20.9° C is the warmest September. The previous record was 18.6° C in 2020.
The mean sea level pressure of 1035.9 hPa on the 11th is the highest September pressure. The previous record was 1033.9 on 23 September 2018.
Monthly Review
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Monthly Meteograms
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Performance Monitoring
The daily rainfall and temperature data are routinely compared against the BoM AWS at Laverton for quality assurance. The daily rainfall is also routinely compared against the Melbourne Water rainfall and river level station on Skeleton Creek at Hoppers Crossing (Hoppers in the table below).
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Units of Measurement
Unless otherwise advised, temperature is given in degrees Celsius (° C) and rainfall in millimetres (mm).
Observation Times & Reporting Periods
The main observation for the day is at 9 am when the precipitation over the past 24 hours is determined, and the maximum and minimum thermometers are also read and reset. The following conventions are used for assigning dates to the observations made:
- Maximum temperature : the 24 hours from 9 am on the date the data are recorded. The maximum temperature will usually occur in the afternoon of that day.
- Minimum temperature : the 24 hours to 9 am on the date the data are recorded. The minimum temperature will usually occur in the morning of that day.
- Mean temperature : the average of the daily maximum and minimum temperatures on the date the data are recorded.
- Daily rainfall : the 24 hours to 9 am on the date the data are recorded. A significant portion of the rain may have occurred on the previous calendar day.
- Monthly rainfall : from 9 am on the last day of the previous month to 9 am on the last day of the current month.
- Phenomena : the 24 hours to midnight on the date the data are recorded.
Climatology & Station Records
Our climatology and station records are based on all available data since 1 April 2017. All annual data are based on complete calendar years commencing in 2018. If a station record is equalled, the date shall be the most recent occasion to conform to standard BoM practice.
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