How Maplequarry reads a night sky
A likelihood score is only useful if you can see what went into it. This page walks through the three factors Maplequarry multiplies together, the real astronomy and space-weather behind each one, and exactly where the model is an approximation rather than a live feed.
Factor 1: Darkness
This sounds obvious — you need it to be dark to see the aurora — but it is the single biggest reason a trip fails. A strong geomagnetic storm during daylight hours produces exactly nothing visible from the ground. Every region on this site is a good latitude for aurora in principle; what actually varies month to month is how many hours of genuine astronomical darkness a night offers.
Around the September and March equinoxes, all four regions get close to equal day and night — roughly 12 hours of darkness — which is also when geomagnetic activity independently tends to spike (more on that below). By contrast, in June, Yellowknife and Whitehorse sit close enough to the Arctic Circle that true darkness nearly disappears for weeks; the sky never gets black enough for a display to register, no matter how active the aurora actually is that night. Churchill and Iqaluit, at slightly lower latitude, keep a thin sliver of darkness even at midsummer, but not enough to make a trip worthwhile.
Why December isn’t automatically the best month
December has the most darkness of any month, but it isn’t always the single best month to travel — it’s simply never disqualified by daylight the way June is. The equinox months add a second real advantage on top of decent darkness: geomagnetic activity itself tends to run higher around the equinoxes, a well-documented seasonal pattern in space weather (the Russell–McPherron effect), which is why Maplequarry adds a small bump to September and March scores specifically, not just to the darkest months.
Factor 2: Regional visibility
The aurora forms an oval centred on the magnetic pole, not the geographic pole, and its everyday position sits at roughly 65–70° magnetic latitude. A location sitting almost directly under that oval sees dim activity on a routine night and a full display on an active one. A location further from the oval’s usual band needs the whole oval to expand equatorward before anything is visible overhead — which is exactly what the Kp index measures (next section).
Yellowknife and Churchill both sit close enough to the oval’s typical position that a merely average night is often enough. Whitehorse sits nearer the oval’s southern edge, so it more often needs a livelier night to produce the same show directly overhead. Iqaluit is further east and more exposed to Atlantic and Baffin Bay weather systems, which shows up in Factor 3 rather than here — its geomagnetic positioning is still solid.
The Kp index, briefly
NOAA’s Space Weather Prediction Center publishes the planetary Kp index: a 0–9 scale, recalculated every three hours from roughly eight ground magnetometer stations worldwide, describing how disturbed Earth’s magnetic field currently is.
| Kp | What it means for the aurora |
|---|---|
| 0–2 | Aurora stays close to the pole, dim, low activity — still enough for Yellowknife or Churchill on many nights. |
| 3–5 | The oval widens and brightens noticeably. Kp5 is also where NOAA’s storm scale begins (G1). |
| 6–7 | Bright, fast-moving displays, visible well south of the usual band (G2–G3 storms). |
| 8–9 | Rare, extreme storms (G4–G5) — the oval can reach the northern United States. |
Maplequarry doesn’t try to predict tonight’s exact Kp value — that changes hour to hour and is genuinely only forecastable a few days out at best. Instead, the “regional visibility” factor encodes each region’s typical exposure: how much Kp activity it usually needs, based on its position relative to the oval’s average location.
Factor 3: Sky clarity
None of the above matters if it’s overcast. Cloud patterns vary meaningfully between these four regions and by month: Churchill’s deep-winter air is famously dry and clear; Yellowknife’s continental climate keeps cloud cover moderate most of the year; Whitehorse and Iqaluit both see more cloud on average, from Pacific-influenced systems moving through the Yukon and Atlantic/Baffin Bay systems reaching Nunavut respectively. Maplequarry folds a representative monthly cloud figure for each region into the final score as the third multiplier.
Solar Cycle 25 and why 2026 is still a strong year
Solar activity runs in an eleven-year cycle, and the current one — Solar Cycle 25 — produced a stronger peak than most forecasters expected, with its smoothed sunspot number climbing above 200 in late 2024, one of the strongest maxima since the 1950s. Different tracking methods put the peak itself at either October 2024 or a second peak around mid-2025 (a “double maximum” pattern the cycle has shown before). Either way, 2025 and 2026 sit in the cycle’s declining phase.
That is not necessarily bad news for travellers: historically, some of the strongest individual geomagnetic storms of a solar cycle occur during the decline rather than right at the peak, and forecasters tracking Cycle 25 into 2026 still expect elevated coronal mass ejection frequency and further G3–G4-class storms. Maplequarry’s regional and monthly factors don’t change year to year, but it’s worth knowing that the broader solar backdrop for 2026 travel is still considered favourable, not a lean year.
What the moon does
A full moon does not erase the aurora — a genuinely active display is still clearly visible — but it does wash out fainter shows and lights up the sky enough to hide subtle structure and colour, especially in photographs. Most aurora photographers avoid shooting within about three days of a full moon unless a strong storm (Kp 7 or higher) justifies it; a new moon reveals the full colour and shape of a display. Maplequarry doesn’t currently factor moon phase into its score — check a lunar calendar for your travel dates alongside it.
What this model is — and isn’t
Maplequarry is a seasonal planning tool. Its 24-hour chamber view for any region and month represents a typical clear night for that combination, built from public daylight-length patterns and each region’s known geomagnetic exposure — it is not pulling live satellite or magnetometer data, and it will not tell you whether it will be cloudy on the specific Tuesday you land. Once your dates are within a few days, check NOAA’s Space Weather Prediction Center for the real-time Kp forecast and Aurorasaurus for citizen sighting reports, and use Maplequarry for the decision that actually matters months in advance: which region, and which week.