Perth has just posted its second-driest May on record and shivered through the coolest mornings ever experienced during the month.

Key points: Perth has had 17.8mm of rain, against the May average of 89.4mm

Perth has had 17.8mm of rain, against the May average of 89.4mm The dry has extended across the state, with farmers forced to "dry seed"

The dry has extended across the state, with farmers forced to "dry seed" The warm weather will continue for the start of winter and over the long weekend

Not since 1964, when the city received a paltry 14.1 millimetres, has Perth received so little rain in May, with just 17.8mm collected for the month this year.

To put that in context, the May average is 89.4mm at the city's official site in Mount Lawley, which has been operating since 1994.

It has been a parched start to the year for other parts of the state, with the driest figures on record recorded for the South West Land Division, which stretches south-west of a line from around Kalbarri on the West Coast to Israelite Bay on the South Coast.

The Bureau of Meteorology (BOM) said the conditions were putting pressure on farmers.

"We've had a very dry autumn but we also had a very dry summer and late spring," BOM spokesman Neil Bennett said.

"It's been an exceptionally long dry period and what that has meant is that unlike previous years, where we had a lot of rainfall in the summer months as a result of tropical systems moving down over the area and dumping big falls, we didn't see that.

"We didn't see a great deal of thunderstorm activity either."

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Mr Bennett said farmers had been "dry seeding" as a result — sowing fields that didn't have subsoil moisture to help crops germinate.

The weather pattern in May was dominated by strong high pressure systems over the south, which blocked rain-bearing cold fronts from reaching the state.

"[The lack of rain] was down to the lack of frontal activity as we moved out of the middle part of autumn into the late autumn, which is typically when we see frontal activity increasing," Mr Bennett said.

Record cool south, searing hot north

The overnight temperatures in May were the coldest ever experienced for the month in Perth, with the city recording a mean minimum of 8.7 degrees Celsius compared to the average of 10.5C.

BOM weather map showing rainfall outlook for winter 2019. ( Supplied: Bureau of Meteorology )

"That's as a result of the lack of cloud cover, the clear skies overnight, due to the presence of the high pressure systems," Mr Bennett said.

Conversely, parts of the north experienced exceptional heat.

Broome had its hottest May on record, notching up a mean maximum of 34.7C, well above its long term average of 31.6C.

"It was the number of days above 35C which was quite phenomenal … they had 18 days of 35C or more," Mr Bennett said.

WA's Pentecost River was looking far drier than normal after the the wet season this year. ( ABC News: Courtney Fowler )

Hot, dry winter on way for east

Winter kicks off with a balmy 26C in Perth on Saturday.

It could be a taste of what is to come, with warmer than average days very likely for much of the country, including WA.

"We're still looking at very warm conditions for much of the state, with high odds of having above normal temperatures, both daytime and night-time as well," BOM manager of long-range forecasting Andrew Watkins said.

The BOM winter climate outlook suggests the dry trend is likely to continue in parts of eastern and central Australia.

The darker red, the higher the chance the area will exceed median maximum temperatures this June to August. ( Supplied: BOM )

But there is not a strong signal towards drier or wetter conditions for WA as a whole.

"For rainfall, it's really only the far southern parts of the South West, those coastal regions going along from Albany through to Esperance, that look like being drier than normal," Dr Watkins said.

"For the rest of the state there isn't a strong swing in the odds towards exceptionally wet or exceptionally dry."

Perth forecast