Icing is unpredictable.
You can expect ice to form on your aircraft with an OAT in the range +4 to -20 degrees C.
Generally speaking it will only form if you are in cloud or visible precipitation. The type that forms, and the rate at which it forms are determined by the type of moisture you fly though.
Stratus tends to be associated with rime icing, and cumulus and the stuff that falls out of it, with clear icing.
Rime tends to build slowly and although it should not be regarded as "safe", can be carried further for longer than clear ice.
Clear ice often builds quickly, is very heavy, and won't go even when you fly into warm air.
As a rule of thumb the freezing level can be predicted (in '000s of feet), by dividing the surface temperature in C by 2. This is not failsafe though
2D