Carnarvon residents have been warned to prepare for flooding that may endanger lives and homes.
The Fire & Emergency Services Authority said flooding was likely tonight and tomorrow after heavy rainfall in the Gascoyne River catchment over the past 24 hours.
More than a year’s rain fell in Carnarvon in just 24 hours this week.
A monsoonal low hovering over the Gascoyne dumped a 24-hour record 204.8mm, smashing the previous record of 119.4mm set on March 24, 1923.
Carnarvon also looks set to break its monthly rainfall record of 212.2mm set in June 1895.
The town's average monthly rainfall for December is 1.8mm.
Bureau of Meteorology duty forecaster Richard Rattley said the low was slowly making its way across the coast.
“The rain-bearing, mid-level circulation of the monsoonal low is moving to the south east over the southern Gascoyne through to the northern goldfields,” he said. “It looks as if Carnarvon has seen the worst of it with the rain to ease on the coast.”
Other areas across the Gascoyne receiving high rainfall over night included Shark Bay which recorded 107.4mm and Denham receiving 80.6mm to 9am this morning.
Roads and highways across the region have been closed including North West Coastal Highway from the Kalbarri turn off to Pannawonica turn off, from the Shark Bay turnoff to Carnarvon and from Carnarvon to the Minilya Roadhouse.
The remainder of the highway is open but subject to flash flooding.
The Main Roads Department is urging motorists to obey road closure signs and take extra care on the roads as flooding is possible, especially at flood ways.
Carnarvon’s record rainfall comes after the town recorded its hottest day in more than three years last Saturday when the mercury reached 44.2 degrees.
The town’s streets are flooded and traffic is severely restricted because of the deluge.
The weather bureau has issued a flash flood warning for Carnarvon, Meekatharra, Laverton, Paynes Find, Kalbarri and Denham.
A monsoonal low is due to move slowly to the south-south east with strong to gale force winds in areas expected well away from the storm’s centre.
The bureau says the low will bring significant rainfall to most of the Gascoyne, the northern Goldfields and south to adjacent parts of the Central West today.
A flood watch is current for coastal streams between Exmouth and Kalbarri.