This is a summer of the little girl La Nina. A summer of too much and too little, in which an unseasonable wet has caused some things to boom and others to flounder.

An egg glut brought on by cool conditions could see the cull of half a million hens, and the laying by July of a million too many eggs each day. Already, 75 million eggs are in storage.

Ventilation companies are dealing with surging numbers of overly damp homes, built into Sydney sandstone and mouldering under cloud and summer humidity.

But there are winners, too. Calls to Beccy Lois's north shore dog walking business have doubled since January. A long wet summer has been a fillip to business. Dogs keep walking, even if their owners do not.

''Dogs love the rain, particularly the labradors,'' she said. ''They think there's nothing better than running from puddle to puddle.''

Sydney has not been this wet in half a decade. Already, twice as much rain has fallen on the city as it did last summer - almost 300 millimetres, with more wet weeks to come.

There have been 38 wet days since December. By autumn, that could easily top the 45 wet days recorded in the summer of 2007-8.

''Considering that we expect February to have 12 wet days - and we've had eight - seven more wouldn't be particularly unusual,'' Acacia Pepler, a climatologist at the Bureau of Meteorology, said.

''It's a complex system that has a variety of peaks during a La Nina year. There's generally cooler sea surface temperatures in the eastern part of the Pacific and warmer ones in our area - that tends to give more available moisture and more rainfall.''

Growers fear that flowers will not bloom in time for Valentine's Day. But water weeds and thistles have benefited from the wet. A shorter flowering period, however, means that the great purple fields of Patterson's curse have been less evident. Ken Lillia, of Panelcorp Autobody Repairs in Atarmon, said car accidents in the wet summer had added about 10 per cent to his business.

''Historically, summer is slower than winter,'' he said. ''[But] if there's a long period of rain or a storm, we expect more business.''

In the animal kingdom, the circle of life is the same: rain has led to more pastures, more rats and rabbits, and in turn more foxes to eat them.

Rain may have washed out weekend sport and deterred beach-goers, but it has not stopped Mary McGreevy swimming. ''I swim anyway,'' the 48-year-old said. ''When it's raining, it's absolutely beautiful. It's so quiet.''

In all, it will be a mixed summer: flood has troubled the state's north, wheat and barley and chickpeas have all suffered, but the wet has vastly improved the outlook for other crops.

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