Where my family comes from in the UK, the way to tell when the soil is ready for beans is to drop the trousers and wiggle your cheeks in the soil. Sit there for a minute. If it feels comfortable and not cold, then it is time to plant.
The weather where I live now, tends to follow Easter and usually corresponds with the last killing frost. This year we had a fairly late easter combined with La Nina and we haven't really felt any signs of winter ending yet. For many years, I can get my beans in the ground by the middle to end of March. Not this year. Even my komatsuna isn't warm
enough in the soil to germinate.