Can I see the northern lights tonight?

The four checks (all of them, at once, where you are)

"Aurora tonight?" is really four questions wearing a trench coat. Miss any one and you see nothing, no matter how excited the internet is:

1. Is the Kp high enough for your latitude? Kp measures global geomagnetic disturbance on a 0–9 scale. What matters is whether tonight's forecast Kp clears the bar for your geomagnetic latitude — your distance from the magnetic pole. Northern Scotland needs roughly Kp 4–5; Yorkshire about 5; the Midlands 5–6; London 6–7. (Iceland needs 1–2, which is why Reykjavik guides look so smug.)
2. Is it dark? Fully dark — not dusk. In British midsummer the answer at northern latitudes is "barely, briefly"; from late August the real season opens.
3. Is your sky clear? Cloud is the great killer. Not "cloudy today" — cloud at the hour you'd be looking. A clearing at 1am is a viewing window; most forecasts never show it to you.
4. Can you see the northern horizon? At UK latitudes the display usually sits low in the north. Trees, hills, streetlights and your neighbour's security lamp all count as cloud.

What time tonight?

At UK latitudes the statistically best window is 22:00–02:00 local, centred on local magnetic midnight. But aurora arrives in sub-storms — surges of twenty minutes to an hour — so a single nightly percentage hides the plot. The practical method: check an hour-by-hour forecast, find the hours where Kp, darkness and low cloud overlap, and treat those as appointments. That overlap is precisely what AurorAlert's hourly strip shows — green hours are go-outside hours.

Approximate visible-display thresholds by geomagnetic latitude; strong storms (G3+) can beat these numbers. The app calculates your exact figure — see how forecasting works.

Why last month's alert was wrong

Three usual suspects. One: the app alerted on Kp alone, and Kp 5 in daylight under stratus is still nothing. Two: the number was a global storm level, not your local need — Kp 5 is a show in Aberdeen and a rumour in Kent. Three: timing — the sub-storm peaked at 23:40 and you looked at 01:00. None of these are your fault; all of them are fixable with an hourly, location-specific forecast that stays quiet otherwise. That's the entire reason AurorAlert exists — the developer got burned by all three from his own back garden in West Yorkshire.

Tonight-night checklist (save this)

• Check the hourly forecast, not the nightly headline — find the green overlap hours.
• Get somewhere with a low northern horizon and no direct streetlight; even ten minutes out of town transforms it.
• Dark-adapt for 15 minutes; every phone-check resets the clock (red-light mode helps).
• Expect grey-green ribbons to the naked eye at UK latitudes; the camera sees colour first — a 3-second phone night-mode shot is your scout.
• Storms surge and fade — if it's quiet, wait twenty minutes before giving up.