Monday, 3 August 2020 - Monthly Climate Summary for Greater Sydney - Product code IDCKGC15L0

Greater Sydney in July 2020: A wet month and above average temperatures

July 2020 was wetter than average throughout Greater Sydney, mostly as a result of a coastal low pressure system which affected the region from the 26th to 28th. The majority of sites reported more than double their average July rainfall. Daytime temperatures were close to, or above average, while overnight temperatures were warmer than average throughout. Very large and powerful waves from the 14th resulted in significant coastal erosion along parts of the Central Coast.

Coastal lows bring above average rain

• Greater Sydney received well above average rainfall throughout the region, with Mangrove Mountain in the north receiving more than 4 times its usual July rainfall.
• The most significant totals were a result of a coastal low pressure system that developed from a trough along the New South Wales coast on the 26th; the heaviest falls in Greater Sydney fell between the 26th to 28th, with widespread 3 day totals exceeding 100 mm.
• This low pressure system resulted in some sites having their highest July daily rainfall on record, with Mangrove Mountain recording the highest total of 136.2 mm for the 24 hours to 9 am on the 27th.
• An earlier Tasman low pressure system affected Greater Sydney from 13th to 15th; this system bought moderate shower activity to the area, but was more significant in terms of the large and powerful waves it produced.
• The passage of winter fronts also produced isolated shower activity throughout the month.
• Sydney (Observatory Hill) reported rainfall on 16 days, which is above the average of 11 days for July.
• Some sites had their highest total July rainfall on record.
• Some sites had their highest total July rainfall for at least 20 years.
• Sydney Airport reported on average 5.8 hours of bright sunshine per day, below the long-term average of 6.7 hours.
• The year-to-date rainfall for Sydney (Observatory Hill) is 1072 mm, above average for the January to July period (828.1 mm).

Above average temperatures

• Daily temperatures were mostly up to 1 °C above average across the region, but ranging from 0.7 °C below average at Cooranbong (Lake Macquarie) to 1.9 °C above average at Katoomba (Farnells Rdl).
• Daytime temperatures were particularly mild across Greater Sydney to start the month, as a result of warm northerly flow ahead of an approaching cold front; most sites exceeded 20 °C on the 1st and 2nd, with Penrith Lakes reaching 24.7 °C on the 2nd, the warmest day of the month.
• Cooler days were experienced during the middle of the month and again on the 26th and 27th, due to the influence of Tasman Lows directing cold southerly airstreams and cloudy skies over the region.
• Overnight temperatures were warmer than average overall, ranging from 0.5 °C above average at Mt Boyce to 2.5 °C above average at Sydney Airport.
• Cloudy conditions resulted in milder minimum temperatures on the 27th where night-time temperatures were 6 °C to 8 °C above average across most areas of Greater Sydney.
• Clear skies and light winds under a high pressure system resulted in cold mornings between the 21st and 23rd, with the coldest night-time temperature of -0.8 °C being recorded at Katoomba (Farnells Rd) on the 21st.
• For Sydney (Observatory Hill) the year-to-date mean maximum and minimum temperatures both lie within the warmest 10% of records (decile 10), with a mean maximum temperature of 23.1 °C (1.4 °C above average) and a mean minimum temperature of 15.1 °C (1.0 °C above average), for the January to July period.

Sydney (Observatory Hill)

• Total rainfall for Sydney (Observatory Hill) was 183.0 mm, which is 190% of the long-term average of 96.3 mm and the wettest July since 2011.
• The mean daily maximum temperature for Sydney (Observatory Hill) was 18.0 °C, which is 1.6 °C above the long-term average of 16.4 °C.
• The warmest day was 23.0 °C on the 2nd, and the coolest day was on the 8th when the temperature reached 15.0 °C.
• The mean daily minimum temperature for Sydney (Observatory Hill) was 9.7 °C, which is 1.6 °C above the long-term average of 8.1 °C.
• The coldest morning was 7.1 °C on the 22nd, and the warmest morning was on the 27th when the minimum temperature was 13.6 °C.

Other phenomena

• A deep low pressure system over the Tasman Sea generated very large and powerful waves along the NSW coast from the 14th, which persisted for several days. The waves resulted in hazardous beach conditions and coastal erosion, particularly along the coastal area near Wamberal, where residents were evacuated due to significant erosion. Peak waves exceeding 11.5 metres were recorded by the wave rider buoy offshore of Sydney. Wind gusts of 109 km/h were recorded at Wattamolla and 96km/h at Norah Head.
• Thunderstorms with small hail were reported across parts of western Sydney and the Central coast on the 12th, following the passage of a cold front.

Extremes Maps Records Summaries Daily observations Important notes the top

Extremes Maps Records Summaries Daily observations Important notes the top

* note: there are gaps in the historical record at this site, so it is possible a higher value has gone unreported

Extremes Maps Records Summaries Daily observations Important notes the top

Extremes Maps Records Summaries Daily observations Important notes the top

Extremes Maps Records Summaries Daily observations Important notes the top