Aurora forecast

Northern lights in Illinois tonight

The aurora reaches Illinois at about Kp 6.7 in the far north of the state and Kp 7.4 at its southern edge. SWPC's highest forecast Kp over the next three days is 2, in the 03-06 UTC block on Mon, Sep 21. Not tonight. The forecast Kp of 2 is well below what it takes for the aurora to reach this far south.

From NOAA’s Space Weather Prediction Center, read Sep 20, 23:14 UTC.

Illinois forecastsLive radar

The oval right now

NOAA’s OVATION model: the chance of aurora overhead 30 to 90 minutes from now, valid Sep 21, 00:19 UTC. Green is a low chance, red a high one.

NOAA Space Weather Prediction Center aurora forecast: the probability of aurora over the northern hemisphere, with the oval drawn in green through red

Rain and snow mean cloud, and cloud is the last thing between a forecast aurora and the sky you are standing under. Each town page carries that town’s own sky cover forecast for the dark hours.

Open the live map with the aurora forecast

Aurora forecast from NOAA’s Space Weather Prediction Center. Original at SWPC

Tonight at Winthrop Harbor

The most poleward town in Illinois with a page, and the first place in the state an aurora reaches. Cloud cover is on each town’s own page.

No tonight

Not tonight. The forecast Kp of 2 is well below what it takes for the aurora to reach this far south.

  • The aurora reaches this place at about Kp 6.7, which is 51 degrees geomagnetic latitude on NOAA's storm scales.
  • SWPC forecasts a highest Kp of 2 (2.00) during tonight's dark hours: quiet.
  • The moon is waxing gibbous, 71% lit, and up for part of the dark hours.

Towns best placed in Illinois

The 24 most poleward of the 791 towns in Illinois with a page. Each page gives tonight’s chance there, the darkness, the moon and that town’s own cloud forecast.

  1. Winthrop HarborLake County · population 6,818 · 51.3° geomagneticKp 6.7
  2. Lake CatherineLake County · population 1,379 · 51.3° geomagneticKp 6.7
  3. AntiochLake County · population 14,329 · 51.3° geomagneticKp 6.7
  4. Channel LakeLake County · population 1,664 · 51.3° geomagneticKp 6.7
  5. RichmondMcHenry County · population 1,900 · 51.3° geomagneticKp 6.7
  6. ZionLake County · population 24,117 · 51.3° geomagneticKp 6.7
  7. HebronMcHenry County · population 1,202 · 51.3° geomagneticKp 6.7
  8. South BeloitWinnebago County · population 7,680 · 51.3° geomagneticKp 6.7
  9. WadsworthLake County · population 3,739 · 51.2° geomagneticKp 6.8
  10. Spring GroveMcHenry County · population 5,711 · 51.2° geomagneticKp 6.8
  11. Beach ParkLake County · population 13,976 · 51.2° geomagneticKp 6.8
  12. Lake VillaLake County · population 8,821 · 51.2° geomagneticKp 6.8
  13. LindenhurstLake County · population 14,408 · 51.2° geomagneticKp 6.8
  14. Fox Lake HillsLake County · population 2,591 · 51.2° geomagneticKp 6.8
  15. Pistakee HighlandsMcHenry County · population 3,454 · 51.2° geomagneticKp 6.8
  16. RocktonWinnebago County · population 7,525 · 51.2° geomagneticKp 6.8
  17. Venetian VillageLake County · population 2,826 · 51.2° geomagneticKp 6.8
  18. Grandwood ParkLake County · population 5,202 · 51.2° geomagneticKp 6.8
  19. HarvardMcHenry County · population 9,194 · 51.2° geomagneticKp 6.8
  20. WarrenJo Daviess County · population 1,376 · 51.2° geomagneticKp 6.8
  21. Fox LakeLake County · population 10,518 · 51.2° geomagneticKp 6.8
  22. ShirlandWinnebago County · population 936 · 51.2° geomagneticKp 6.8
  23. Lake SummersetWinnebago County · population 2,048 · 51.2° geomagneticKp 6.8
  24. OrangevilleStephenson County · population 756 · 51.2° geomagneticKp 6.8

Every town in Illinois with a page

791 towns at 48 degrees geomagnetic latitude or higher, which a strong storm reaches. The figure after each is the Kp it takes there.

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How far south each storm level reaches

NOAA’s space weather scales state the geomagnetic latitude each level of geomagnetic storm reaches, and the places its aurora has been seen from. The geographic latitudes are those lines converted with the geomagnetic dipole; the aurora sits low on the northern horizon there, and overhead far poleward of it.

StormGeomagneticCentral USEastern USNorthern EuropeNOAA says the aurora
G1 MinorKp 560°52°N51°N61°Ncommonly visible at high latitudes: northern Michigan and Maine
G2 ModerateKp 655°47°N46°N56°Nhas been seen as low as New York and Idaho
G3 StrongKp 750°42°N41°N51°Nhas been seen as low as Illinois and Oregon
G4 SevereKp 845°37°N36°N45°Nhas been seen as low as Alabama and northern California
G5 ExtremeKp 940°32°N31°N40°Nhas been seen as low as Florida and southern Texas

Source: NOAA space weather scales, swpc.noaa.gov/noaa-scales-explanation. Below Kp 5 the oval contracts more slowly; this section runs the line from 66 degrees geomagnetic at Kp 0 to the scale’s 60 degrees at Kp 5.

Kp by 3-hour block

SWPC’s planetary K index forecast, three days ahead. Kp is a single number for the whole planet, from magnetometers around the world, on a scale of 0 to 9 in thirds.

Block (UTC)KpLevelSeen fromCentral US
0.67Quiet65° geomag.57°N
1.67Quiet64° geomag.56°N
2.00Quiet64° geomag.55°N
1.67Quiet64° geomag.56°N
1.33Quiet64° geomag.56°N
0.67Quiet65° geomag.57°N
1.33Quiet64° geomag.56°N
1.33Quiet64° geomag.56°N
1.67Quiet64° geomag.56°N
1.67Quiet64° geomag.56°N
2.00Quiet64° geomag.55°N
1.67Quiet64° geomag.56°N
1.33Quiet64° geomag.56°N
0.67Quiet65° geomag.57°N
0.67Quiet65° geomag.57°N
1.67Quiet64° geomag.56°N
1.67Quiet64° geomag.56°N
1.67Quiet64° geomag.56°N

The forecast is for the planet, not for your sky. A block at Kp 5 means the field is disturbed enough for the aurora to reach 60 degrees geomagnetic somewhere along the night side; whether you see it depends on being on the night side, on darkness, and on the clouds.

Other states with aurora pages

What this means

Each place is placed by its geomagnetic latitude, measured from the geomagnetic dipole pole, and compared with the reach NOAA states for each storm level on its space weather scales: G1 (Kp 5) about 60 degrees geomagnetic, G2 55, G3 50, G4 45, G5 (Kp 9) 40. Reading that backwards gives the Kp a place needs. Below Kp 5 the oval contracts more slowly and the line runs from 66 degrees at Kp 0 to 60 at Kp 5.

The forecasts have different horizons and the pages keep them apart: OVATION is the only thing that knows whether an aurora is out now, and it reaches 30 to 90 minutes ahead; the planetary Kp forecast runs three days; the 27-day outlook names likely active days and is not a forecast of any one night. None of them knows the clouds, which is why a town page reads its own forecast for those.

Sources

From NOAA’s Space Weather Prediction Center: the OVATION aurora forecast, the planetary K index forecast, the 3-day forecast, the 27-day outlook, its watches, warnings and alerts, and the real-time solar wind. Read Sep 20, 23:14 UTC.

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