Sydney got a splash of rain early on the weekend, but today's rain will drench the city and soak the west. All of Sydney is likely to experience its heaviest rain in at least two and a half months. Today, the majority of Sydney is likely to get more rain than it has received in the past two and a half months combined. No suburb has had more than 55m since the end of June, with Penrith only picking up 7mm. Western Sydney has gone more than half a year since it had rain as heavy as it will receive today and into tomorrow morning. Penrith and Richmond should get more than 25mm today, their heaviest since the first day of March. Rain has already begun in eastern parts of Sydney due to a shallow northeasterly flow ahead of the main low and trough. The northeasterlies are bringing in moisture from the ocean, leading to consistent light rain. The city has already picked up 10mm, while almost all suburbs west of Hornsby and Parramatta were still dry at midday. This afternoon the northeasterlies will strengthen as the low and trough nears Sydney. This will lead to heavier rain in the east and the development of rain across the west. The vast majority of western suburbs should gain 25-40mm from this system, while the east should pick up 40-70mm by 9am tomorrow. On Tuesday rain will ease back to the odd shower during the morning as the low and trough move offshore. There will be substantial breaks in the rain during the day, with sunshine returning. Dry conditions will return again on Wednesday with only a few showers a chance later in the week in the east. Western suburbs could be in for another stretch of dry weather.