From Rocketpedia

Motor Prep

Motor prep will not begin if any of the following conditions are met:

• The 24 hour average temperature has been below 18 degrees
• The wind is observed or forecast to exceed 42 knots for the next three hour period
• There is a forecast of greater than a 20% chance of lightning within five nautical miles of the launch pad for the next 48 hours.

Launch Weather Constraints

Temperature

Launch criteria the temperature exceeds 107 degrees Fahrenheit for more than 30 consecutive minutes.

In no case may the vehicle be launched if the temperature is 35 degrees Fahrenheit or colder.

Wind

The peak wind speed allowable at the launch site is 20 knots.

Splash pattern based on latest winds aloft data is within the recovery area. Note: Launch azimuth and elevation may be adjusted to ensure the vehicle lands in the recovery area. In no case may the vehicle be launched if the required elevation is more than 20 degrees from vertical.

Precipitation

None at the launch pad or within the flight path

A "Good Sense Rule" is in effect for launch which states: "Even when constraints are not violated, if any other hazardous conditions exist, the launch weather officer will report the threat to the launch director. The launch director may hold at any time based on the instability of the weather."