Constantly evaluate your activity. A chance of rain shouldn't be much of a detriment if you are sport climbing at Smith Rock, but could prove to be life-threatening if you are attempting the Diamond on Colorado's Longs Peak. Timing is everything with forecasting . Don't let your goals cloud your thinking, or change your forecast. If there is uncertainty in the forecast, then there should be uncertainty in your plans.
Forecasting is an ongoing process.
Constantly re-evaluate whether or not you should proceed. Imagine the worst weather scenario for the day. Consider the consequences of being caught out in the weather. Once you are out in the backcountry, you must keep watching the weather, all the time weighing your options to turn back, continue on, or stall, and wait to see if the weather gets better or worse. And if you are caught in a thunderstorm, get to low ground as soon as possible .