Police and fire officers are appealing for information after being called out to 68 grass fires within the last six days.
Several of the fires are believed to have been started deliberately.
Blazes tackled by the officers include Garnswllt in Ammanford, Tairgwaith in Gwaun Cae Gurwen and a four-hectare fire at Kilvey Hill, Swansea.
Ammanford Fire Station has been involved with the blazes for the last three days assisted by the Mid and West Wales Fire Service.
“People need to remember that arson is a crime,” said police sergeant Terri Harrison.
“We believe that several of these fires have been lit deliberately, and all the details have been passed on to the police for further investigation.”
Thousands of hectares of countryside are destroyed by fire every year, which includes open spaces and wildlife habitats, and many of these fires are preventable.
Farmers and landowners are allowed to burn heather, grass, bracken and gorse on their land until the March 15 and in upland areas this is extended to March 31.
But a Burn Plan must be in place to ensure that the fires are burning safely and are constantly controlled.
Burning outside the burning season can result in penalties of up to £1,000.
Meanwhile PS Harrison stressed that fire can quickly get out of control and have a devastating impact on the people who live in their respective communities.
“Deliberate fires are dangerous, unpredictable and can quickly spread,” he said.
“They can also have a detrimental impact on the people living nearby, as grass fires can effect breathing, irritate skin and eyes and cause chest pains.”
They also pose a severe threat to wildlife, and can cause widespread damage to their habitats.
Fire fighters often have to tackle the blazes in extremely dangerous and challenging conditions.
“These fires place unnecessary pressure on frontline services and put our communities in harm’s way,” concluded Terri Harrison.
“We all know that accidents can happen but there are people out there in our communities who are deliberately setting fire to our countryside.
"This this a crime, for which they will be prosecuted.”
If anyone has information concerning the deliberate fire starters, they are asked to unanimously report their details to Crimestoppers by calling 0800555111.
They can also call the police on 101, quoting crime reference 2200095064.
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