The most severe warning applies to counties Galway, Mayo, Clare and Kerry, where rainfall totals of 40 to 50mm are forecast between Friday evening and Saturday evening, locally higher on hills and mountains.

A yellow warning also applies to counties Offaly, Limerick and Tipperary for the same 24-hour period, with 30 to 40mm of rain expected. Only Ulster and north Leinster will remain relatively dry on Saturday.

Hill and coastal fog is also forecast in those areas, in variable northwesterly winds with fresh and gusty periods along Munster coasts.

Saturday's heavy rain spell will come between dry periods, with bright weather forecast for most of this Friday and again from Sunday.

Temperatures will drop once the rain clears on Saturday night, with lows of between 2°C and 6°C and grass frost. Sunday will be a crisp, much colder day with maximum temperatures not to exceed 10°C and widespread frost at night, with lows ranging between -2°C and 3°C.

Dairy management

With the weather taking a definite winter turn, it's time to focus on drying off cows and keep an eye on heifer weights. In some areas, alternatives to silage will be needed.

Beef management

Beef farmers, too, are at a crucial juncture for feeding and should take a hard look at their cattle's diet. Housing calls for good animal husbandry, including clipping and pneumonia control.

Sheep management

Farmers in the Sheep Welfare Scheme might take advantage of the lousy weather on Saturday to check on their ewe numbers ahead of the Decemeber census. On the breeding side, both rams and ewes need particular nutrition attention on mid-season lambing flocks.

Tillage management

In the fields, there has been some progress on winter planting and despite the bad forecast for Saturday, more weather windows seem to be available later on. It is getting late in the season, though, and seed rates may need to be increased. We also have some spraying advice for crops planted earlier.