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You are correct in saying

You are correct in saying weather may play a role. It has been a cool, wet spring in many parts of the country. Cool weather with temperatures below 75 degrees Fahrenheit can delay flowering. Another reasons could include dry soil or overcrowding. 

Sometimes a plant won't produce flowers if it receives too much nitrogen. Squash likes low nitrogen and higher phosphorus and potassium. If you think it might be too much nitrogen, you might apply some amendments that contain phosphorus and potassium to balance the nutrients. Ask a local garden nursery for options and timing.

Once it's warm enough, expect most summer squash to flower 35 to 45 days from germination.