Morning
the longest shadow you see in the day is 3\early in the morning and near the sunset...
when its its sunrise and evening.
That depends where you are on the planet. Your shadow would be longest if you were standing on a rotational pole at the time of equinox. At this point your shadow would be infinity long as it would be "projected" into space. However as a rule of thumb one's shadow is longest when the sun is rising or setting but high enough to cast your shadow.
The sun casts the longest shadows immediately after sunrise and immediately before sunset.
Early Moring and juts before the sun sets .
Summer would probably have the the shortest shadow because the sun is right over us and winter would have the longest because the sun isn't right over us. The length of the shadow really doesn't depend on the seasons. It is really about where the sun is in the sky. But in order for there to be an actual shadow, the sun must be visible. So in summer you would find the most shadows but not the longest. You can get a long shadow in any season as long as the sun shines.
Just after sunrise, or just before sunset.
For a given shadow object, and at a given time of the day, the shadows will be longer in winter, for then the Sun will be lowest in the sky
At dawn and dusk.
at noon the shadow is point sized {smaller} and in morning and evening the shadow is the longest.
Just over the horizon.
longest