Move the entire journey, not just the first forecast
Leaving three hours later moves every checkpoint arrival by three hours. It does not mean comparing the same hour at every location. RoadAheadNow matches each estimated arrival to the corresponding hourly forecast interval, then repeats the calculation for four departure windows.
Keep the comparison fair
An incomplete window must not win just because the missing checkpoint might have been the worst one. We only identify a lower-concern departure when every checkpoint has the required forecast inputs and a successful alert check across all four windows. Otherwise, the comparison is marked incomplete.
Treat the duration as an assumption
The listed baseline is a rounded planning duration, not a live traffic estimate. Add a realistic stop allowance. We spread that allowance across the checkpoints, rather than pretending to know where you will stop. A long meal, an overnight break or congestion can move your arrival outside the shown hour.
Read the local clock labels
The departure picker uses the device time zone shown next to it. Results show local time at each checkpoint. Across a time-zone boundary, a one-hour clock change is not an extra hour of driving. This matters on routes such as Nashville to Knoxville and Flagstaff to Albuquerque.
Know what an improvement means
A lower weather-concern category only means that the selected weather triggers are less pronounced in that sampled window. It is not a probability of a crash, a prediction that a road will reopen or an instruction to drive. Review the underlying reasons and the official road information before acting.
Official sources
NWS hourly forecast documentation
Reviewed October 5, 2026. Check the current source before travelling.