Bermuda grass is a warm season grass, and therefore it should never be planted before late spring. The temperature of the ground is key to the success or failure of the seed. If the ground is too cold or hasn't thoroughly defrosted from winter, the seed will not be able to germinate and grow. The soil must be at least 65 to 70 degrees in order to plant the grass. This means that your area will need to have experienced several days of temperatures above 80 degrees in order to get the soil to the right temperature. Depending on where you live, this usually means that you will plant Bermuda grass in the late spring or early summer. Moisture level is also key to the success of grass seed, however this can be taken care of via irrigation and is not dependent on the weather like soil temperature.
Because it is a warm season grass, it is often best to plant the seed during the warmer months. Although it may seem more enjoyable planting the seed in the spring, when the weather is bearable, this could result in bare spots on your lawn because the temperatures may not be high enough to facilitate proper seed germination. The warmest months in the summer, when temperature are around 90 to 100, are generally the best to plant this particular variety of grass seed.
It is also important that you remember Bermuda grass needs to be planted at least 90 days prior to the first frost if you live in a Northern state and 60 days if you live in a Southern State. Therefore, take this into consideration when you are deciding when you want to plant. Most experts recommend that you plant in late July or early August, as this will give you sufficient time before winter hits.