Certified GKH Gardening Expert
This would depend on the bulb. With winter flowers, such as tulips, then it is much too late. These should be planted to go through the coolest part of the season. If these are summer bulbs then you can still plant them as long as they remain moist, and not too hot.
If you could tell me which ones you will be planting then I can better assist you with what to plant, and when.