Iowa · 6 towns compared
Northern lights in Iowa: tonight’s chance
Iowa needs a strong storm, but its flat, dark farmland gives that storm one of the cleanest northern horizons in the Midwest.
Tonight at Des Moines, IA
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Reading the SWPC Kp forecast and the cloud forecast…
| Kp forecast during the dark hours | not yet forecast |
|---|---|
| Kp needed here | 6.8 (G3 strong) |
| Cloud cover in the dark hours | loading |
| Dark sky (Sun 18° down) | 8:08 PM to 5:53 AM CDT |
| Moon | 13% lit |
| Right now, OVATION (30 to 90 min) | loading or unavailable |
| Magnetic latitude (AACGM) | 51.0° |
Hour by hour, CDT
7 PM
Kp –
– ☁
No
8 PM
Kp –
– ☁
No
9 PM
Kp –
– ☁
No
10 PM
Kp –
– ☁
No
11 PM
Kp –
– ☁
No
12 AM
Kp –
– ☁
No
1 AM
Kp –
– ☁
No
2 AM
Kp –
– ☁
No
3 AM
Kp –
– ☁
No
4 AM
Kp –
– ☁
No
5 AM
Kp –
– ☁
No
6 AM
Kp –
– ☁
No
Rules checked · Built by Radif Partners · How the answer works
- Kp to see it from Des Moines
- 6.8
- Storm level needed
- G3 (Strong)
- Kp for aurora overhead
- 7.5
- Most clear dark hours
- September
Every Iowa town needs a geomagnetic storm to see the northern lights, and the whole state fits in a narrow band of thresholds. Mason City, near the Minnesota line, sits at 52.5 degrees magnetic latitude in the AACGM model and needs about Kp 6.5, a G2 (Moderate) storm on the NOAA scale. Dubuque needs Kp 6.6, Cedar Rapids Kp 6.7, and Des Moines about Kp 6.8, a G3 (Strong) storm. The boundary between those two storm levels runs right across the state. Sioux City, on the Missouri, needs Kp 6.7, more than Dubuque at the same latitude, because magnetic latitude falls toward the west. For Des Moines, NASA POWER cloud averages run from 44% in September to 65% in January, and September, November and October give the most clear dark hours. The tool opens on Des Moines; type any Iowa town or ZIP code to see tonight's verdict there.
Flat land, open sky
Iowa is not a natural aurora state by latitude, but it has an asset that eastern cities lack: a horizon. Most of the state is gently rolling farmland with few trees on the skyline and small towns spaced far apart, so from almost any gravel road outside a town the northern sky runs down to the ground. When a storm pushes the aurora to the edge of Iowa's range, it sits low, within the bottom few degrees of the sky. A ridge, a tree line or the dome of a city can hide it completely; an Iowa section road usually does not. The trade is that the state needs a real storm, a G2 (Moderate) level at best, and no amount of darkness changes that.
Two corners break the flat pattern. In the northeast, the Mississippi has cut deep bluffs, high places with long views but also valleys that block the north. In the west, the Loess Hills rise along the Missouri River, wind-built ridges that offer a raised viewpoint above the river plain.
A state that straddles two storm levels
From Mason City to Des Moines the threshold climbs only 0.3 Kp, but that small step crosses the line between G2 (Moderate) and G3 (Strong) on the NOAA scale. In practice, the strongest G2 blocks of a storm can reach the northern counties and leave the center of the state just short. The Kp index page explains how the three-hour blocks are read. The west-east tilt is just as visible: Sioux City and Dubuque share a latitude, yet the eastern city needs less, because the geomagnetic pole sits east of Iowa's meridian.
What Kp does this town need?
Kp to see aurora from here
6.5
| Magnetic latitude (AACGM) | 52.5° |
| Kp for aurora overhead | 6.8 |
| Storm level | G2 Moderate |
| How often that level comes | about 360 days per 11-year cycle |
View line: the more southern of the SWPC oval rule and the NOAA G scale latitudes at each Kp.
Clear Iowa nights through the year
Iowa's continental climate gives it fewer of the lake clouds that weigh on Michigan and Ohio. In Des Moines the cloud amount bottoms out in September, and the autumn months rank highest for clear dark hours. Summer nights are short but not empty: on June 15, full darkness in Des Moines still lasts 4.5 hours. Winter brings long nights, 11.5 hours in mid-December, but also more overcast and bitter wind on open ground. The Minnesota page shows how much lower the thresholds get across the northern border, and the Illinois page covers the other bank of the Mississippi.
Kp needed across Iowa
| Town | Magnetic latitude | Kp to see it | Kp overhead | Storm level |
|---|---|---|---|---|
| Mason City | 52.5° | 6.5 | 6.8 | G2 (Moderate) |
| Dubuque | 51.9° | 6.6 | 7.0 | G2 (Moderate) |
| Sioux City | 51.7° | 6.7 | 7.2 | G2 (Moderate) |
| Cedar Rapids | 51.4° | 6.7 | 7.3 | G3 (Strong) |
| Davenport | 51.0° | 6.8 | 7.5 | G3 (Strong) |
| Des Moines | 51.0° | 6.8 | 7.5 | G3 (Strong) |
Darkness and clouds by month in Des Moines
| Month | Dark hours | Dark sky, 15th | Mean cloud | Clear dark hours |
|---|---|---|---|---|
| January | 11.2 h | 6:47 PM to 6:00 AM | 65% | 3.9 h |
| February | 10.2 h | 7:21 PM to 5:35 AM | 64% | 3.6 h |
| March | 9.0 h | 8:53 PM to 5:52 AM | 64% | 3.2 h |
| April | 7.3 h | 9:35 PM to 4:53 AM | 61% | 2.9 h |
| May | 5.6 h | 10:22 PM to 3:58 AM | 62% | 2.1 h |
| June | 4.5 h | 11:00 PM to 3:29 AM | 55% | 2.0 h |
| July | 5.0 h | 10:49 PM to 3:51 AM | 46% | 2.7 h |
| August | 6.7 h | 9:59 PM to 4:38 AM | 48% | 3.5 h |
| September | 8.4 h | 8:58 PM to 5:21 AM | 44% | 4.7 h |
| October | 9.8 h | 8:05 PM to 5:55 AM | 53% | 4.6 h |
| November | 11.0 h | 6:30 PM to 5:28 AM | 57% | 4.7 h |
| December | 11.5 h | 6:25 PM to 5:54 AM | 64% | 4.1 h |