Seven of Wales's international aid charities have joined forces for an appeal to help save lives in Darfur, Chad and the Central African Republic.
Millions in Darfur have been forced to flee for their lives
The charities have united under the umbrella of Disasters Emergency Committee Cymru.
On Thursday, paralympian Dame Tanni-Grey Thompson will make a televised appeal for donations.
Ongoing conflict in the region is said to be affecting 4.5m people, and the situation could be set to worsen.
Charities are warning that storms due in the coming weeks will bring the risk of deadly conditions including diarrhoea and malaria, with children, pregnant mothers and the elderly among the most vulnerable.
Nearly one in three of Darfur's population have been forced to flee for their lives into camps
Four million people in Darfur are dependent on humanitarian aid for their survival
In Chad, 147,000 people are internally displaced
Some 232,000 refugees have fled from Darfur into Chad since the crisis began in 2003
Facts from DEC Cymru
The fact that the leading agencies have joined together for the appeal illustrates the severity of the situation, according to Jeff Williams, Chair of DEC Cymru.
The charities involved in Wales include the British Red Cross, Oxfam Cymru, Tearfund, Cafod Wales, Save the Children, Christian Aid and Help the Aged.
"We are seeing one of the greatest concentrations of human suffering right now in Darfur and Chad and the impending rains will make the situation even worse," he added.
"We have been keeping people alive but access is already severely hampered by conflict and the rains will make it much harder for us to respond if we don't act now."
The situation in Darfur and Chad is "desperate" says Dame Tanni
Money raised by the appeal will go towards providing shelter, clean water and sanitation as well as emergency care, food and vital items such as water buckets, blankets and soap.
Dame Tanni said that every penny would make a difference to the appeal.
"The people of Darfur and Chad are in a desperate situation" she said.
"Millions have been forced to flee their homes and more than 4.5 million are dependent on humanitarian aid to survive - help is needed on a huge scale."
Dame Tanni Grey-Thompson's appeal will be shown on BBC1 Wales on Thursday at 1855 BST and 2235 BST. A message in Welsh by Garry Owen will be broadcast on S4C at 1925 BST on Thursday.