The heat will be an issue. Keep an eye on things particularly during the warmest days of summer and be proactive about keeping the plant area under 110F. Toward this end, having several smaller boxes that you can bring inside or shade as needed might be beneficial for you.
The biggest issue as others have suggested is watering. Skipping a day can be destructive, particularly when you have a hot afternoon.
If you can have deeper, wider planting boxes you'll find that the watering is easier and less picky, because the amount of soil will moderate that issue, as well as act as a heat sink so the temperature extremes are evened out a bit.
Potting mix is important. Make sure whatever mix you use includes water absorbing/storing media, compost, and soil. We make our own mix based on the book "square foot gardening" (recipes available online) which provides a good all around mix for excellent plant growth with good protection from most types of infrequent neglect.
An herb garden should be fairly straightforward though, and I'd be tempted to establish each herb in its own medium size pot so you can rotate and move them around be based on conditions.