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Unsettled weather has continued to plague parts of Spain over the last few days, with heavy rain triggering floods.

After months of severe drought, Spain’s worst in over half a century, it is reported that May 2008 has been the country’s wettest since May 1971. Since the beginning of June, low pressure has continued to dominate bringing more wet weather, mostly across northern and eastern parts of the country. Last week, heavy rain across Spain’s Basque country triggered severe floods as streets were turned into rivers.

The recent rainfall has helped to address the deficit left in reservoirs over the last few months, so much so that Spanish authorities recently cancelled a controversial drought relief plan. This involved running a pipeline to redirect water from the Ebro River to the northeast region of Cataluña.

The rain has also caused a headache for the organisers of Expo2008 in Zaragoza in the run up to its opening. The event, perhaps ironically given the topic this year of “water and sustainable development” suffered some flooding as the Ebro River overflowed.

Further heavy rain caused severe flooding in Albacete, Castilla-La Mancha on Sunday with over 75mm (3 inches) of rain falling in 24 hours. The State Meteorological Agency (AEMET) is forecasting further showers for the north and east today but with conditions expected to improve over the next few days.

While eastern states of the US have been reeling under a heat wave the last few days, an unusual “winter” storm has brought June snow across the northwest.

The National Weather Service (NWS) issued snow warnings and advisories earlier this week as the storm moved east across Washington and Oregon States. Residents of East Oregon woke Monday morning to a scene more akin to winter, with snow blanketing gardens and with white out conditions on the roads. Heavy snow fell in the Cascades forcing trucks crossing the mountain passes to use tyre chains. Meanwhile the Department of Transport announced that it was the first time in 30 years that snowploughs had been used in June to clear Steven’s Pass.

The unusual cold and snowy weather is being attributed to this year’s La Nina, which brought parts of the US their snowiest winter on record. Today the storm has moved on to Montana and Idaho prompting further warnings from the NWS. As much as a foot of snow (12 inches) is forecast.

Across eastern states of the US it has been quite a different story though. Warm moist air from the Gulf has been drawn northwards across the east, bringing heat wave conditions as far north as New York. It looks as though the worst is now over though with showery weather moving east today bringing lower temperatures.

With the early arrival of the south west monsoon at the end of May, Mumbai received the heaviest rainfall for the last seven years in its first week. The south-west monsoon spread into the eastern province of Orissa earlier in the week, with Keonjhar receiving just over 90mm (3.54 inches) of rainfall.

Between 2001 and 2007 the most rainfall Mumbai received over nine consecutive days was 60mm (2.36 inches). According to the Indian Meteorological Department (IMD), Santacruz in Mumbai recorded 421.8mm (16.6 inches) of rain in the last nine days. This is already more than the rainfall for the entire month of June in 2004.

With an upper air circulation pattern lying off the eastern coast, the monsoon rains are expected to continue to move across the state over the next two days. The IMD forecast further spells of rain or thunderstorms, and strong gusty winds later this week.

Many parts of southern and central Mexico have been flooded after more than a week’s worth of heavy rains.

The southern Mexican state of Oaxaca has been worst affected. More than 7,000 people were evacuated from their homes as flood waters continued to rise. So far, at least five people have lost their lives in the floods. Heavy rain and floods have also affected the oil-producing state of Veracruz along the Gulf of Mexico coast.

The rainy season is now underway across much of Mexico. Since last Wednesday, the recent heavy rains have been particularly severe and persistent. Mexico’s rainy season starts around late May or early June and continues through into September and sometimes into October.

During the rainy season, most of the rainfall occurs during sharp afternoon thunderstorms, but recently, persistent and torrential rain has moved off the near Gulf, leading to widespread flooding.

In late October 2007, a week of torrential rain caused devastating floods across the banana-growing state of Tabasco. The low-lying area was completely submerged in water and over 700,000 people were affected.

Forecasters are expecting further heavy rain across much of central and southern Mexico over the coming weekend, but expect the rain to ease into the start of next week

Thunderstorms and record flooding drenched America’s Midwest again on Friday, with severe storms prompting warnings that stretched all the way from Oklahoma to Wisconsin.

Over the last month the Midwest has suffered under a constant barrage of storms as hot and humid air across eastern states has collided with cooler air coming in from the west. Over this time, Iowa has totted up over 450mm (18 inches) of rain and is now buckling under the strain with thousands having to leave their homes.

Iowa has been worst hit by the current floods with the Iowa Homeland Security and Emergency Management describing them as a “one in five hundred year” event. On Friday the Cedar River saw levels far surpass those ever recorded before, with 83 of Iowa’s 99 counties being declared disaster areas. The last major floods to hit the Midwest were during the Great Flood of 1993. These floods were among the most costly and devastating to ever occur in the United States.

Normally the rivers and land might have coped with the recent heavy downpours. However, heavy winter snow followed by above average rain early in spring has left the ground saturated. With more storms expected over the weekend, the situation looks likely to worsen before it improves.

Heavy rains that hit southern and eastern China have left at least 55 people dead and 7 missing, while over one million residents have been evacuated, according to the government and state media on Sunday.

The rains have also wrecked over 10,000 homes, with landslides covering roads throughout Jiangxi, Hunan, Hubei, Anhui, Gaungdong and Guangxi. More than 1.27 million people have been evacuated, with large swathes of farm land submerged and economic losses already amounting to over $145 million (£73.6 million).

Prosperous Guangdong province has been hardest hit, with at least 28 people dead or missing. Rains there have led to the worst flooding in the Pearl River delta in up to 50 years, reported the Xinhua news agency.

In parts of Guangdong, up to 415mm (16.6 inches) of rain fell in just 24 hours from Friday to Saturday. The Guangdong government issued an emergency flood alert throughout the province as levels in tributaries to the Pearl River hit or surpassed warning levels.

The state meteorological bureau warns that water levels in major rivers are also threatening towns in Jiangxi and Guangxi provinces. Rains are expected to continue to pound southern China, including earthquake-affected Sichuan province, through to Tuesday.

Over the weekend, two truckers battled against raging flood waters in the Pilbara region of Western Australia.

Stormy weather has been affecting Western Australia over the last week. In Perth there were numerous calls to the emergency services at the weekend as a cold front moved through bringing heavy rain and strong winds. Many of the calls were from the Rockingham area, southern Perth, hit only last Monday by a tornado.

The recent rain, however, will have done little to address the worsening drought across the country, said to be the worst in over a century. The drought is said to be drying up Australia’s Outback. It has also forced the closure of the world’s largest cattle farm, Anna Creek. The farm which extends across an area larger than Wales has seen the grazing land depleted.

The Australian Bureau of Meteorology has recently declared May 2008 the driest on record. Low rainfall over the autumn, in fact over the last 12 months, has seen the extent of severe drought extending. Northeastern parts of New South Wales and southern areas of Queensland are amongst the exception though, having benefited from some decent rainfall, all due to the 2007/ 2008 La Niña.

Severe flooding from monsoonal rains has left at least 50 dead and displaced hundreds of thousands of people.

One of the worst affected regions is Assam where flash floods swamped over 500 villages in waist deep water leaving 300,000 people homeless. Over the past few days Assam and neighbouring Arunachal Pradesh have seen a series of mudslides that destroyed many buildings leaving scores of people injured.

Monsoonal rain across India is often heavy and persistent and can produce some of the world’s highest rainfall totals. Recent rains in parts of India have been particularly intense and have fallen earlier that usual. The monsoon begins sweeping across the Indian subcontinent in early June, reaching the rest of northern India before the beginning of July. This year’s annual rains have swept across the country two weeks before schedule, the earliest for over a century.

Despite the severity of flooding in places, the rains across the north provided immense relief to many from the blistering heat. Temperatures today dropped to around 34C (93F) - which is at least 6C below normal.

Forecasters are of course expecting further falls of heavy thundery rain across the north and northeast of India over the coming days.

After some of the worst flooding in decades, forecasters in China are warning of more heavy rain with further floods to come.

Torrential rains have battered eastern and southern China during the past few weeks, forcing over 1.5 million people out of their homes. While forecasters expect flooding during the Chinese monsoon season, many areas across the south have experienced record amounts of rainfall.

One of the worst affected areas is the southern province of Guangdong. Here the Pearl River Delta has seen its worst flooding in over 50 years. Flash flooding around the delta has washed away roads, submerged fertile farmland and caused several landslides.

The flooding comes after the devastating earthquake in the Sichuan province on 12 May. Emergency and rescue aids have been stretched to their limits. Forecasters are expecting yet more heavy rain across southern, and in particular, northern parts over the coming few days.

So far, these summer floods have claimed around 200 lives, and with more heavy rain expected, the death toll could rise further. In 1998, torrential monsoon rains caused flooding and mudslides that killed 4,000 people and injured thousands of others.

Parts of South Africa have been battered by freak storms that led to flooding and mudslides across the country on Wednesday.

One of the worst affected areas is KwaZulu-Natal, where at least four people lost their lives after flash floods inundated homes and swept cars away. Rescue teams continue to search for scores of people who are still missing. Scottburgh in KwaZulu-Natal received the highest rainfall amount with 128mm (5 inches) falling in 24 hours on Wednesday.

In Durban, thousands of motorists were caught in grid-locked traffic as deluges caused mudslides which blocked roads. In some areas of the city there was more than a foot of floodwaters.

The main mechanism involved with this heavy rainfall event was due to the ridging action of a strong high pressure system (with a central pressure of 1044hPa) into the southern Indian Ocean, with subsequent pressure rises and onshore flow along the south-eastern and eastern coastline of South Africa. Locally torrential downpours developed, along with strong to gale force winds giving rise to dangerous sea conditions.

Further heavy rain continued in places along the KwaZulu-Natal coast during this morning, with over 74mm (3 inches) being reported in a 4 hour period at Lois Botha Airport in Durban.

The worst is not yet over, however, as forecasters warn of further downpours to come over the next few days. But by the end of the weekend, drier and brighter weather is expected across most parts.