With an average altitude of 2,500 metres, Dhamar - some 100km south of Sanaa - is one of the coldest regions in the country; temperatures have recently fallen to around minus four degrees Celsius.
Ali Mohammed al-Hamdi, director of the Dhamar-based Agriculture and Irrigation Office, said the first frosts began in mid-November but got worse in mid-December "destroying almost all remaining crops, even 'qat' [a mild narcotic leaf] trees covered with cloth sheets".
Covering plants with cloth is one way of protecting them from frost, according to Fuad al-Kawri, agricultural guidance director at the same office. Also helpful, he said, was "burning firewood and tyres around farmland in the early morning and increasing the frequency of irrigation flows from two to three per month".
But preventive measures are proving futile this year.
Abdulwahab Mohammed al-Alayyah, chairman of the Agricultural Cooperation Association (ACA) in Dhamar, said they had received hundreds of complaints from vegetable growers that their crops had been destroyed in the first week of January. "We still need to investigate the real causes of such unprecedented frost before suggesting some workable solutions for affected farmers," he said.
Ahmad Qasim, a salesman at ACA, said sales of fertilizers, pesticides and agricultural equipment had dropped over the past month as a result of the frosts. "Farmers fear that using fertilizers and pesticides will make their crops more vulnerable to the cold, particularly as frosts are expected to last until the end of January," he said.
Preference for 'qat'
Al-Kawri told IRIN that 80 percent of the governorate's 1.3 million people depend on farming. "Thirty percent... grow 'qat', particularly in the plains in the eastern part of the governorate, while the remaining 70 percent grow grain, fruit and vegetables."
"These days, I am covering my crops with three layers of cloth sheets, as one or two layers are not enough to protect them from frost," said Ali Hassan al-Jamid, a 25-year-old 'qat' farmer from Dhaf village, where 1,200 farmers lost their potato, tomato and wheat crops to frost last week, he said.
Al-Jamid said that as a result of steadily dropping temperatures over the past five years in the Jahran area of Dhamar, where about 75,000 people live, thousands of farmers had switched to 'qat' cultivation.
"I make about YR 60,000 (US$300) per month from my 'qat' farm to cover the family's basic needs. If I had no cloth sheets, I would have lost our livelihood source," he said.
According to al-Hamdi of Dhamar's Agriculture and Irrigation Office, severe frosts can increase locally grown food and 'qat' prices three-fold, due to limited supply.
Livestock fodder prices are similarly affected, as frost destroys forage crops, said Abdu Yahya, a farmer from the governorate's Ans District. "I got up early on 8 January to find that my 'berseem' [a forage crop] was destroyed... Over the next two months, I will need to spend a lot of money to get fodder for my two cows and donkey," he said.
According to the government's Central Statistics Organization, more than 70 percent of the country's estimated 23 million people depend on agriculture or livestock farming as their main source of income. However, the sector accounts for only 20.1 percent of gross domestic product.