Fairbanks or Yellowknife, Tromsø or Reykjavik?

Dipole latitude is the distance from the IGRF-14 centered dipole pole, which is where the auroral oval centers. Higher values sit closer to the oval on a quiet night. The G level row maps that value onto SWPC's typical latitudes, and is approximate for the reasons given on the geomagnetic latitude tool.

The monthly table gives civil night on the 15th of each month, the hours with the sun at or below -6 degrees. The mini ribbons draw the same thing as shapes. The no-darkness row gives the longest run of nights without civil night, and the dark season row counts days with at least 4 hours of civil night between 18:00 and 06:00.

Moon-free dark hours add up every night of the current month when the sun is down past -6 degrees and the moon is below the horizon. The live row reads each town's OVATION cell after the page loads.

Start with the month you can travel. The monthly table shows whether both towns are dark then. Next compare dipole latitude: the higher town sits closer to the oval on quiet nights. Then check the moon row for the month and plan the trip around its darkest week.

Cloud is the input the table cannot settle. Glow reads a live NWS forecast for US towns only. The cloud row tells you which towns will have a live reading on the night; each town page adds NASA POWER's long-term monthly average.

Travel cost, light pollution, road access and local weather history are outside Glow's data. So is any forecast of activity beyond the next 30 to 90 minutes. Every figure in the table is computed from coordinates and dates, or read live from NOAA.