A U.N. refugee agency official said on Friday that daily crossings by people fleeing violence in Ukraine have slowed in recent days, saying warmer weather might be a factor.

“We have seen a slowdown, a general slowdown,” said Matthew Saltmarsh via videolink from Poland, adding that warmer weather might be a factor. However, he warned that any escalation of violence in the Western Ukrainian city of Lviv might cause crossings to rise again.