Northern Lights Denver – Visible Tonight? Kp 7.3 Needed

From Kp 7.3 the aurora can be seen on the horizon in Denver, from Kp 9 high in the sky. NOAA's live 3-day Kp forecast and tonight's dark hours.

Aurora over Denver

  • Denver lies at 47° geomagnetic latitude. From Kp 7.3 an aurora can show low over the northern horizon, from Kp 9 it can reach overhead – on a dark, clear night away from city lights.

Dark hours in Denver – the next 7 nights

  • Mon, October 5: fully dark from 20:05 to 05:31, moon 26 % lit
  • Tue, October 6: fully dark from 20:03 to 05:32, moon 17 % lit
  • Wed, October 7: fully dark from 20:02 to 05:33, moon 10 % lit
  • Thu, October 8: fully dark from 20:00 to 05:34, moon 4 % lit
  • Fri, October 9: fully dark from 19:58 to 05:35, moon 1 % lit
  • Sat, October 10: fully dark from 19:57 to 05:36, moon 0 % lit
  • Sun, October 11: fully dark from 19:55 to 05:37, moon 1 % lit

Which Kp is enough where?

  • Reykjavik: On the horizon from Kp 0 · High in the sky from Kp 0
  • Tromsø: On the horizon from Kp 0 · High in the sky from Kp 0
  • Edinburgh: On the horizon from Kp 2 · High in the sky from Kp 4
  • Oslo: On the horizon from Kp 1.3 · High in the sky from Kp 3.3
  • Stockholm: On the horizon from Kp 2.3 · High in the sky from Kp 4
  • Helsinki: On the horizon from Kp 2.3 · High in the sky from Kp 4.3
  • Copenhagen: On the horizon from Kp 3.3 · High in the sky from Kp 5.3
  • Hamburg: On the horizon from Kp 4.3 · High in the sky from Kp 6.3
  • Berlin: On the horizon from Kp 5 · High in the sky from Kp 7
  • London: On the horizon from Kp 4.3 · High in the sky from Kp 6.3
  • Warsaw: On the horizon from Kp 5.7 · High in the sky from Kp 7.7
  • Munich: On the horizon from Kp 7 · High in the sky from Kp 9
  • Paris: On the horizon from Kp 6 · High in the sky from Kp 8
  • Toronto: On the horizon from Kp 4.7 · High in the sky from Kp 6.7
  • Data: NOAA Space Weather Prediction Center

How long it gets fully dark in Denver

  • The night after the 15th of each month: how long the sun stays more than 18° below the horizon. An aurora needs that dark sky – far north, summer has none at all.
  • January: 11 h 9 min · 18:35–05:43
  • February: 10 h 14 min · 19:07–05:20
  • March: 9 h 3 min · 20:37–05:39
  • April: 7 h 29 min · 21:15–04:44
  • May: 5 h 56 min · 21:58–03:54
  • June: 4 h 58 min · 22:31–03:29
  • July: 5 h 27 min · 22:22–03:49
  • August: 6 h 56 min · 21:36–04:32
  • September: 8 h 31 min · 20:39–05:10
  • October: 9 h 52 min · 19:50–05:41
  • November: 10 h 55 min · 18:17–05:12
  • December: 11 h 24 min · 18:13–05:37

How to see it

  • Look toward the pole: North in the northern hemisphere, south in the southern – away from city lights.
  • Use your phone's night mode: A camera shows colours the eye cannot see yet – the aurora often looks grey at first.
  • Be patient: The aurora comes in bursts, often 20–30 minutes apart.
  • Check the clouds: Without a clear view to the horizon nothing helps.

FAQ

  • What does the Kp index mean? The Kp index measures from 0 to 9 how disturbed Earth's magnetic field is. The higher it is, the farther the auroral oval moves toward the equator. From Kp 5 NOAA speaks of a geomagnetic storm.
  • When is the best time for the northern lights? Around magnetic midnight – in central Europe roughly between 10 pm and 2 am – and around the equinoxes in spring and autumn, when storms are a little more frequent.
  • How reliable is the forecast? The Kp forecast for the next hours is quite good, for two or three days only rough: solar storms take one to three days to reach Earth, and their exact strength often only shows shortly before.