Tasmania has been "unseasonably" warm by day and night. Minimum temperatures in the 24 hours to 9am Sunday were generally two to six degrees above average. In the lower Derwent, Campania and Geeveston were six degrees above the average minimums for May. In fact, all districts except for the West and South Coasts, had minimum night time temperatures of up to six degrees above average. Daytime temperatures were also several degrees above average with many locations reaching six to seven degrees above the May average. Campania a balmy 23 and Bushy Park, 21, both reached seven degrees above average today. The warm spell can be attributed to the jetstream (fast flowing air currents in the upper atmosphere) keeping cold air well south of the State. Overnight temperatures tonight and daytime temperatures tomorrow should remain generally above average. However, balmy conditions will be short lived with the arrival of a strong cold front late on Monday.