Thursday, 1 March 2018 - Seasonal Climate Summary for Greater Sydney - Product code IDCKGC25L0

Greater Sydney in summer 2017-18: Another hot and dry summer

Summer 2017-18 was warmer than average, with several heatwave events experienced during December and January. Several monthly and summer records were set for single hottest days and warmest days overall, especially in the west of Greater Sydney. Overnight temperatures were also warmer than average over summer, with December being particularly warm. Rainfall was below average across the region, with fewer than average significant events. Late season rainfall brought some relief to the region.

Dry across Greater Sydney

• Rainfall was below average across the region; January was particularly dry, with December and February receiving closer to average rainfall
• Total rainfall for Sydney (Observatory Hill) was 197.8 mm, which is 67% of the long-term average of 296.7 mm
• The southwest of Greater Sydney was more affected by the drier conditions, with many sites in that area only receiving 40% to 50% of their typical summer rainfall
• The most significant rainfall event of the season occurred during the last week of summer as a cold front and associated low pressure trough moved across Sydney on 25 February bringing widespread rainfall; totals of 50 mm to 90 mm were recorded in the northern half of the region and 30 mm to 50 mm across the south, for the 24 hour period to 9am on 26 February; St Ives recorded 91.2 mm, the wettest day of summer across Greater Sydney
• Other notable rainfall events occurred at the start of summer when rain and thunderstorms moved through the region on 3 December, producing widespread falls of more than 10mm, with further showers that continued for several days; 8 January also brought showers and thunderstorms to the region with a trough of low pressure that resulted in 43.0 mm being recorded at Mount Wilson over the 24 hours to 9am on 9 January
• Significant rainfall events were fewer this summer with Sydney (Observatory Hill) only recording four days with 10 mm or more of rain, compared to the average of eight days; similar trends were observed across the region
• Sydney (Observatory Hill) recorded rain on 38 days over summer, which is close to average for this season; in the southwest, Camden and Bankstown recorded rainfall on 23 days, below their summer averages of 31 and 32 days respectively
• Sunshine at Sydney Airport was close to average, with around 7.7 hours of hours of bright sunshine on average per day over summer

A summer of records in the west

• The mean daily maximum temperature for Sydney (Observatory Hill) was 27.6 °C, which is 1.9 °C above the long-term average of 25.7 °C, and the fifth warmest summer on record
• Mean daily maximum temperatures were much warmer than average across the region, particularly in the west, where Penrith Lakes recorded an average of 33.5 °C, which is 3.6 °C warmer than usual and its warmest ever summer on record, beating the 16/17 summer record; several other sites in the west equaled their warmest ever summer, including Camden, Richmond and Horsley Park
• Summer 17/18 was characterised by several heatwave events during December and January; a number of sites set records for their hottest December and January days and hottest overall for mean maximum temperatures for both months
• The heatwave in early January also produced new summer records, with several sites recording their hottest ever summer temperature on record; Penrith Lakes recorded a maximum temperature of 47.3 °C, the hottest on record and also the second hottest day ever recorded in Greater Sydney (below Sydney's all-time record of 47.8 °C at the old Richmond site on 14 January 1939)
• A record number of hot days 35 °C or higher were experienced in the west, with Penrith Lakes recording 38 days hotter than 35 °C during summer, four more than the previous record of 34 days set last summer, and more than double the typical number of hot days for summer
• Overnight temperatures were also warmer than average; the mean daily minimum temperature for Sydney (Observatory Hill) was 19.9 °C, which is 1.5 °C above the long-term average of 18.4 °C and the equal eighth warmest on record
• The start of summer brought particularly warm overnight temperatures with several sites having their highest December mean daily minimum temperatures on record; several records were also set for consecutive number of warm nights of 20 °C or more during December, including Sydney (Observatory Hill)
• The morning of 20th December was particularly warm with Mangrove Mountain and Horsley Park recording their warmest summer night (highest daily minimum temperature) on record; at 9am on the 20th, Sydney (Observatory Hill) had already reached 35.3 °C, the second-highest 9am temperature on record at the site
• January and February saw overnight temperatures return to closer to normal, with most sites recording mean daily minimum temperatures within 1 °C of average

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top