IT may officially be the start of summer but gale warnings are expected to be issued later today as rain continues to lash much of Scotland.

The severe weather warnings follow a month in which a jet stream brought cool, wet and windy conditions for much of May. Forecasters have said the end is in sight, with sunnier weather expected towards the end of the week.

But although the poor weather has been bad news for many gardeners and tourist attractions, there has already been a horticultural silver lining in the many clouds over a famous attraction in Argyll, with Arduaine Gardens reporting "astounding" rhododendron displays.

Maurice Wilkins, head gardener and property manager at the National Trust for Scotland's Arduaine Gardens, south of Oban near Kilmelford, said the wet cool weather may have put off some visitors, with numbers down "by a fair bit".

But the conditions have been perfect for these plants from the cool parts of Asia, he said, adding that he had never seen anything like it in his 24 years at Arduaine.

"Our main display is normally from the end of April till the end of May, but they look as though they will last another few weeks, which is astounding," he said.

A Met Office spokesman said the jet stream - which consists of ribbons of strong winds moving weather systems around the globe - has been across the UK bringing low pressure and with it cool, wet and windy weather.

"But over the next few days what we will see is the jet stream move to the north which will mean the pressure builds bringing better weather," a spokesman said.

"It follows a bad May. Not the wettest, but it has been very wet up till May 27 when we had 149 per cent of rainfall we would normally see in May. That doesn't include the last couple of days which have been very wet. Mean temperatures have also been low, 1.2 degrees below average."

The spokesman said he was confident there would soon be a marked change in the weather, but only after the next couple of days.

"Monday it is downhill once again," he said. "After a relatively dry morning, winds will strengthen during the afternoon and it will become very wet and windy across all areas, by evening. It will be very wet indeed across the Western Isles.

"We could see severe gales across the islands and it is likely we are going to be issuing a yellow 'be aware' wind warning, because of the time of the year."

The change is expected to begin on Wednesday through to Friday when pressure builds with much drier much sunnier weather. "By the time we get to Friday we could be seeing temperatures of 20 or 21c with more sunshine and lighter winds."

He said there could be some rain again, but the high pressure looked as though it would be established across the north of the UK throughout much of June.

At the National Trust for Scotland's Arduaine Gardens, Mr Wilkins said the wet and cool weather had made it an "amazing" year for some of its displays.

"Not only is the spring flowering season greatly extended, but it's an amazing year for the tender rhododendrons in which the garden specialises. Arduaine has probably the largest collection anywhere," he said.

"These flamboyant shrubs originate in the warmer temperate parts of east Asia, such as NE Burma, North Vietnam and Yunnan in SW China and fill the garden with fragrance and colour - a walk around the garden on a cool, damp evening is breath-taking and the display is likely to remain in good shape for a while yet.

"The camellia collection is hanging on and the azaleas too, many also fragrant, are still coming into flower, surrounded in many places by bluebells. Altogether it's a real feast for the senses and a surprise for those who've not visited before."