A decision on whether to cancel the WRC Rally Sweden is likely to be made overnight after warmer than usual weather in the Karlstad region of Sweden.
Colder weather is forecast later in the week - in time for competitive stages - but reconnaissance is scheduled to take place on Tuesday and Wednesday local time, which could damage the roads with a lack of snow and ice.
"It's frightening how quickly the weather and the forecasts can change, Rally Sweden CEO Glen Olsson told Autosport magazine.
"We had a good layer of ice on our roads and promising forecasts this Friday.
"Now the situation is significantly changed."
The last time the event was cancelled was back in 1990 though it has been close on several other occasions.
All possibilities remain open from cancelling it altogether, to pushing from a three-day (Fri-Sun) to two-day (Sat-Sun) event or pushing ahead as planned.
Reigning world champion Sebastien Ogier won the season-opening event in Monte Carlo in mid-January. Kiwi Hayden Paddon is scheduled to drive one of two works Hyundai WRC cars in the event.