Frost? or computer error?

everywhere but the southern bit  

Looks like we (in southern bit) are going to be below 10C min. until middle of the month. Still quite chilly for Squash / Courgettes. However, mine are nowhere near ready to plant out yet,and will cope with a  pot-on to larger pot to hold them back a while yet.

I've been switching on central heating 3-4 time in the past two weeks.