Answer: No it is not too hot. Just give them (and yourself) plenty of water, and control the weeds to cut down on competition. Mulch on the soil will help in both respects.
Pumpkins take around 80-120 days from planting to harvest depending on variety. Count on about 100 days for most varieties. Early June planting would therefore yield pumpkins about early September. That is fine because the fruit will keep, but you may want to wait another two or three weeks to get them in a bit later.
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