Blimey, if you think you need to be "brave" to venture out of your hotel in Hammamet, I suggest you don't go to Casablanca!
One person's "freezing" is another person's "pleasantly warm"; I have a friend in Cyprus, where we live half the year, who's done up in woolies and shivering in front of the fire when the temperature gets down to 22!
We've been to Tunisia in October and had daytime temperatures of around 24, and at the end of February/beginning of March with the thermometer knocking around 22/23 and wall-to-wall sunshine. I don't doubt Mrs O's experience of the weather, but remember that Tunisian weather, like ours, can be unpredictable. Most sources will tell you to expect about 16/17 deg in February and 20 in October, but these are averages and you could be lucky and strike a warm spell, or unlucky and strike a cold one.