"Much of the southern soya belt needs rain in the next few days," Safras soya specialist Odineia Santos said by phone. "Western Rio Grande do Sul and some parts of western Parana, parts of Santa Catarina and Mato Grosso do Sul need rain."
Independent forecaster Somar on Friday predicted that a cold front was due over the region after February 23 but No 3 soya state Rio Grande do Sul would not receive sufficient showers to relieve the drought stress on plants.
Crops in No 2 Parana and No 5 Mato Grosso do Sul states are better off than in Rio Grande do Sul, as they are more mature and have received more consistent rainfall since December.
US and European soyabean and meal prices have been on the rise as of late over concerns of damage from the dry weather to Brazil's southern soyabean states.
Brazil's center-west soya states have gotten regular rainfall over the crop season and are well into harvest.
Brazil's Celeres consultants reduced slightly their soyabean harvest forecast to 62.22 million tonnes on February 10 from 62.69 million tonnes it expected a month earlier.
Last week, the US Department of Agriculture also pared back its estimate for the Brazilian soya crop to 63 million tonnes from its previous estimate of 64 million.