Focus Ireland has said emergency accommodation used for homeless families is scarce as the tourism sector continues to thrive.
Hotels and B&Bs are booked out due to holidaymaker reservations. As a result, many homeless families are finding it increasingly difficult to find a bed, the homelessness agency said.
The Department of the Environment yesterday published new figures which show there had been a 55% rise in the number of families presenting homeless in the country since the start of the year.
Sister Stanislaus Kennedy from Focus Ireland (pictured) said a lack of social housing was to blame.
"They come to us and we have very few alternatives for them, because there is very little social housing, and furthermore they can't afford to pay the rent," she said.
"They only place we can place them is in a B&B or in a hotel, and that has become increasingly difficult over the summer because of the tourist season," she said.
"I have been working in this area for 30 years (and) I have never seen anything so bad. It's deeply serious."
According to the Department of Environment, the number of homeless adults urgently needing a bed is at a high of 3,258.
Its report also shows that in the first six months of this year the number of families seeking immediate help increased from 401 to 620, while there were over 1,300 children in emergency accommodation, a 52% rise.