Official training begins "today" (7 February KST) for some events (Biathalon, Luge, Ski Jumping) under what will be relatively cold conditions, but with temperatures above what I suspect are considered the minimum competition thresholds. For example, the minimum temperature for holding an FIS World Cup Nordic event is -20ºC. Forecast temperatures for the Biathalon center are -17ºC at 8 am, rising to -8ºC at noon.
Training for the Men's Downhill starts "tomorrow" (8 February KST). Temperatures, however, are expected to be warmer, but still crisp at -13ºC at 9AM and -10ºC at noon.
The good news for opening ceremonies is that temperatures are expected to moderate over the next few days. The situation at present [1500 UTC 6 February (0000 KST 7 Feb)] features a cold flow originating over interior Asia. The 925-mb (about 750 m above sea level) temperature sits at about -16ºC, which explains the cold surface observations noted above.
Over the next few days, temperatures warm gradually and by 1200 UTC 9 February (2100 KST 9 February), roughly an hour after the start of opening ceremonies, the 925-mb temperature sits at a far more tolerable -2ºC.
The one issue in that forecast might be the westerly flow. Currently, however, the Korean Meteorological Agency forecast is calling for light southwest winds (1 m/s equates to 2 knots).
The opening and closing ceremonies sometimes feature displays or activities that are very weather sensitive. Closing ceremonies for the Salt Lake City Games featured, for example, hot air balloons.
I suspect the Pyeongchang forecast team will be keeping a close eye on the winds (as well as other weather parameters) as the opening ceremonies approach.