Spanish ski resorts are watching business melt away as a lack of snow and unusually warm weather force them to close or operate just some of their pistes.

"We have not been able to open at all this year. We are talking about the worst thing that could happen," said Agustin Ramirez, the manager of the Valdesqui resort near Madrid as he stood in front of a closed ticket booth.

The 40-year-old resort located some 60 kilometres (40 miles) from the Spanish capital has 27 pistes of different levels of difficulty that normally draw around 1,500 customers on a weekday -- and up to 3,500 on weekends.

But on a recent visit its parking lot with its sweeping views of the peaks of the surrounding Madrid mountains was empty except for three staff vehicles and the pistes were covered in brown grass.

Of Spain's 32 ski resorts, eight including Valdesqui were closed for skiing on Friday due to the lack of snow and mild temperatures, according to the website of the Spanish Tourist Association of Ski and Mountain Resorts.

None of the 24 resorts that were operating had all of their trails open -- and those that did operate pistes relied on expensive man-made snow to draw skiers.

"It is artificial snow, it is not the same as natural snow but you can ski on it. This year the weather is like this, we have to deal with what we have," said Fernando Cortes as he took a break from skiing under a clear blue sky at the Puerto de Navacerrada resort.

Only two of the nine pistes at the resort located about a dozen kilometres from Valdesqui were open on Friday.

They provided a total of 625 metres of skiable surface running between pine trees out of a total of 9.125 kilometres that could be available under ideal weather conditions.

The resort has 63 snow cannons which it uses to keep the pistes open.

The cost of making artificial snow, though, can be prohibitive.

The La Pinilla ski resort near the central city of Segovia has spent 65 percent of its revenues this season just on making snow, according to its director Angel Gonzalez Pieras.

"The cost has been brutal," he said, without giving figures.

The resort, which has 196 snow cannons, reopened on Friday after being closed for three days due to a lack of snow, with four pistes out of 24 open.

The lack of snow has led ski resorts to cut back on hiring. Valdesqui usually takes on up to 120 workers during the winter season but it is making do this year with just the nine employees who work there year-round.

Ski rental shops and other businesses like hotels and restaurants that rely on an influx of snow seekers to the resorts have also taken a hit.

"Business is awful. This is the worst year that I have seen in my 75 years," said Roman Verdesoto as he stood surrounded by racks of skis at the ski equipment rental shop he has run in Puerto de Navacerrada for 48 years.

"Even if it snows now half the season is gone including the best part, which is the Christmas holidays."

Spain ended 2011 with its driest December in 23 years, according to the national weather office.

Average precipitation in Spain in December 2011 was just 25 millimetres or 30 percent of the average for the month and January has continued to be unusually dry and warm.

Some ski resorts are expanding their non-slope activities, providing trails for mountain bikers and hikers or opening spas and restaurants, to draw visitors even when snow is low.

Last Saturday 150 people used the bike trails at the La Pinilla ski resort, compared to 300 who hit the ski slopes that day.

"There will always be ski seasons like this. You just have to factor it into your plans," said Ramirez of the Valdesqui resort.