Aurora towns ranked by geomagnetic latitude

The widest gap between neighbours falls between Anchorage and Duluth, 6.6°. 3 neighbouring pairs sit within 0.5° of each other (Reykjavik and Yellowknife; Minneapolis and Seattle; Seattle and Portland, Maine), close enough that their order means little.

Two groups stand out. Five towns sit above 60 degrees on the dipole: Fairbanks, Anchorage, Yellowknife, Reykjavik and Tromsø. They fall inside SWPC's 60 to 75 degree band, where its aurora page says aurora can be seen on more than half of all nights. The other five, all in the lower 48, sit between 52 and 56 degrees and need a geomagnetic storm to bring the oval into view. No town sits in between, so the choice of group matters more than the order inside it.

Inside the far-north group the gaps are small. Reykjavik, Yellowknife and Tromsø sit above 66 degrees, the Kp 0 edge, and Fairbanks just below it. For those four, darkness and weather say more than this ranking does. Inside the lower 48 group, Duluth leads and is the only town above SWPC's typical G2 latitude of 55 degrees.

How to use it. If you can pick any of the 10 towns for a few nights, the top five give the most nights with the oval overhead or close by, as long as your dates fall inside their dark season. If you live near a lower 48 town, the ranking tells you how big a storm you need: by SWPC's edge rule Duluth needs one Kp step less than Minneapolis, Seattle, Portland, Maine or Buffalo. For any other town, the geomagnetic latitude calculator gives your own value and the Kp to latitude chart turns it into a Kp.

Limits. A centered dipole is a first approximation of Earth's field. Models with higher-order terms can shift a town by a degree or so, enough to cross a Kp step in SWPC's rule. The order holds for towns more than a degree apart; the near tie at the top, Reykjavik and Yellowknife, does not. SWPC also calls its Kp to latitude relationship approximate and says it describes averages, so treat the Kp column as a guide to storm size, not a switch.

The order does not follow the map. Yellowknife ranks above Tromsø although it sits farther south on the map; Minneapolis ranks above Seattle although it sits farther south on the map.

Geomagnetic latitude is the single best predictor of how often the oval reaches a town, because SWPC's own rules are written in it. It does not change with the season or the moon, so this ranking is fixed until the next IGRF model.

Glow rotates each town's GeoNames coordinates into the IGRF-14 centered dipole frame, using the three degree 1 coefficients for 2025.0 published by NOAA NCEI. The Kp column applies SWPC's rule of thumb: the oval's equatorward edge sits near 66 degrees geomagnetic at Kp 0 and moves 2 degrees per step. SWPC calls that rule approximate.

For your own coordinates, use the geomagnetic latitude calculator. The background is in geomagnetic latitude explained, and every threshold is listed on the methodology page.