99 Honda accord, South Florida. For the past 4 days every morning when I go to leave for work around 8:30am my car will crank over but will not start. Then everyday when I get home from work around 5:30pm it fires right up and runs fine. I've already replace the Main relay that didn't work, any suggestions?

 

Sounds like a thermal failure.

In the morning and in the evening, can you hear the Main Relay click and the fuel pump prime?

Do you have a lot of charms/keys on your key ring? Remove them and retry.
Have you tried jiggling the key in the morning while cranking to see if the car tries to start?
If the ignition switch is worn out, in the cold morning everything is contracted, during the day with the heat parts expand and the contacts make when warm allowing starting in the evening.

Check for any stored codes as well, there may have been an intermittent code from a while back that may lead you to the root cause.

Other than that, start with basics, Fuel, Air, Spark.