Sydney has picked up over 200mm of rain since Tuesday with a further 88mm falling on the cities gauge in the 24 hours to 9am this morning. A deep and slow moving low pressure system off the coast is to blame for the recent downpours. The rain has come as a shock to most after a relatively dry start to the month for Sydney, with a prior total of just 17mm. The last 72 hours has doubled the monthly average total rain for July and brings the cities wettest July in 61 years. The 24 hours to 9am on Friday has generally been the wettest with a torrential 130mm falling on Terrey Hills. Chatswood gained a further 115mm to 9am and is their heaviest July rain in 52 years and in 40 years for any month. Cronulla has gained 257mm in the last three days after getting 126mm to 9am, their heaviest July daily total in 66 years. The heaviest rain is moving offshore as the low spins further east through the Tasman towards New Zealand, with showers easing over the weekend and tending isolated by Sunday.