I.over [美 ˈoʊvər, 英 ˈəʊvə]副over often appears as the second element of certain verb structures in English (blow over, knock over, pore over, etc). For translations, see the relevant verb entry (blow, knock, pore, etc).
Underneath that is "ice-cemented" permafrost, containing higher levels of ice that formed when scant water vapour in the air was deposited as frost over hundreds of thousands of years.
He says they are "slightly concerned" with frost over the next couple days -- due to colder temperatures and a clear sky -- but most areas should not be affected.