Much of South Australia and New South Wales have been dealt one of its coldest May days on record with help from extensive cloud and rain. Temperatures have stayed as much as 10 degrees below average, eight-to-13 degrees colder than yesterday. Many centres have been within a degree-or-so of their May record low maximum. In South Australia parts of Adelaide have struggled to warm past 10 degrees today due to a slow-moving pool of cold air over the region. This cold air pool has not only kept the sun out, but has brought the biggest downpours in over a year to parts of the state. Both Elizabeth and Parafield, in Adelaide's north, have been enduring their coldest May day in 34 years. By 2pm it had still not even reached 12 degrees. Adelaide itself has been shivering in potentially its coldest May day in 25 years. By 3:45pm it had only reached 12.3 degrees, seven below average. The last time the city had a colder May day was in 1987, when 12.1 was the maximum. The record low maximum for May is 11.2, set in 1892. Other South Australian centres which have are still on target for their coldest May day in at least 15 years are Cleve, Minnipa, Whyalla, and Strathalbyn. By 2pm Cleve had only reached 9.4 degrees. In NSW, a separate weather system has done a similar job, delivering a gloomy and wet day to central and southern parts of the state. Some places have only just reached 10 degrees, including parts of western Sydney. Both Penrith and Richmond became cloudy early in the day, as a result had only reached 11 degrees by 3pm. If it doesn't warm above 13 degrees by 9am Friday, today will have been their coldest May day in more than 15 years. In western NSW the cloud has been most beneficial, at least regarding rainfall, given how dry it has been this autumn. Mudgee has had 24mm so far, its wettest day since early autumn. West Wyalong has had its wettest day of the season, despite only gaining nine millimetres in the six hours to 3pm. The low pressure trough causing this rain is tracking east, which will allow the bulk of the rain to clear from western NSW overnight and clear from Sydney by about lunchtime on Friday. It won't be the end of the wet for western NSW, with a pool of cold air due to cross the region during Friday. It will bring more cloud but only a few light showers, amounting to just a few millimetres. Both western NSW and SA will have to put up with more cloud this weekend due to a weak front. Again, showers should generally be light and brief. It won't be until early next week before sunshine warms the bones again, when a high pressure system takes over. However, this high will bring onshore winds, low cloud and a few showers to the NSW coast, including Sydney.