Much of the decent rain that has fallen across Victoria since Sunday has avoided Melbourne, but it is all about to change. The heaviest showers have been to the west, north and east of the city. The CBD and most inner suburbs have only seen a couple of millimetres. Residents will only have to wait until Tuesday night or Wednesday for heavy showers to arrive. A slow-moving low pressure system will send heavy bursts across much of southern and mountain Victoria, including Melbourne during the next few days. Between now and the end of the week, 10-20mm of rain should fall with potential for more than 30mm in some suburbs, particularly in the southeast. This is likely to be the heaviest rain in months. It has been a dry last few months. The city had only received six millimetres of rain during the first two weeks of May, almost 50mm short of the monthly average. And this comes after a fairly dry April when less than half the monthly average rain was recorded. Other areas of the state which should make up for recent dry is Gippsland. After a dry start to the month the region is on target to pick up similar rainfall to Melbourne. Come the weekend, much of the state will be between about a third of the way or half way to their average monthly rainfall. A few wetter exceptions are Port Fairy on the west coast and Kanagulk in the north. Both recently picked up their heaviest May rain in at least a decade with about 30mm falling in less than a day. Port Fairy has now exceeded its monthly average of 64mm and Kanagulk has 86 percent of its 10-year average of 35mm.