In my experience most nobile hybrids nowadays do not need very cold winters, but the critical criteria is dryness for them to bloom.
For window sill culture, if you can achieve min temp to around 15 c but completely dry, you would probably be able to flower them, but be sure to give them some very bright light. Winter sun does them no harm in a south facing window.
The trick is to discipline yourself to leave them alone for two months or so, hard to do if you love your plants.
Andrew
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