Tromsø Aurora ForecastKYOKKO NAVI

Will you see the northern lights in Tromsø, Norway tonight?

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Kp forecast Solar wind OVATION Clouds

Next 3 nights

Tap a night to see its hourly numbers.

“Look outside now!” alerts

Seeing the aurora in Tromsø

Tromsø is a harbor city in northern Norway, right under the aurora zone. You can see the lights even on quiet nights, but the coastal weather is often cloudy.

Season
September–March
Kp needed (rough)
Kp 1–2
Best time (local)
about 21:00–02:00

Where is the aurora right now?

Live aurora probability over day and night. Tap anywhere to see conditions there.

Drag to move · pinch (or scroll) to zoom · twist with two fingers to rotate · double-tap to zoom in

10→50→90% View line (low on the horizon) Daylight Likely visible Aurora, but cloudy or bright Clouds (whiter = thicker) 1Nearby spots

Best spots nearby

Where it's likely visible now

48-hour outlook

Hourly score. Shaded bands are dark hours; the lower strip shows cloud. Tap a bar to see that hour's numbers.

Score Dark hours Clouds (darker = more)

Space weather and sky now

3-day Kp forecast

Geomagnetic activity in 3-hour blocks. The dotted line marks the Kp at which aurora starts to show low on the horizon here.

Kp 0–4 Kp 5–6 (storm G1–G2) Kp 7+ (G3+) Observed / estimated

Pick your dates: darkness & moonlight

Aurora strength can't be forecast more than 3 days ahead. Pick nights with long darkness and little moonlight, then check the Kp forecast just before you go. Tap a date for details.

Darker green = darker sky, less moonlight Kp: NOAA 27-day outlook maximum (rough)

Did you see the aurora?

If you did, we'd love you to post your photos or tonight's forecast with #KyokkoNavi. It helps the next travelers catch the show.

#KyokkoNavi #northernlights #aurora #極光ナビ
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スコアの考え方How the score works

今夜の見えやすさ（0〜100）は、次の4つを掛け合わせた目安です。確率ではありません。

  • 磁気活動：NOAAのKp予報を、観測地の地磁気緯度で「地平線に見える目安のKp」「真上に来る目安のKp」と比べます。直近2時間は太陽風の磁場Bzが南向きなら上乗せします。
  • 暗さ：太陽高度を端末内で計算し、−5°より暗くなるほど加点、−16°以下で満点です。
  • 晴れ：Open-Meteoの低層・中層・上層雲を重み付けして実効雲量にします（低い雲ほど強く遮る）。
  • 月明かり：月が出ていて明るいほど少し減点します。

オーロラは数十分単位で急に変わるため、あくまで出かける判断の目安です。

地図の「いま見えていそう」は別の判定です。OVATIONの出現確率（真上、または極側8°以内の値の6割）が10%以上あり、太陽が十分沈んでいて、現在の雲量が多すぎない地点を表示しています。OVATIONを取得できないときは、Kpから推定したオーロラ帯で代用します。

「近くで見えやすい場所」は、基準点のまわり約±220kmを約44km間隔で区切った121地点の雲量予報（Open-Meteo、1時間ごと）を使います。陸地の地点だけを対象に、「出現確率 × 暗さ × 晴れの割合」を見える度（0〜100）として比べます。陸地の判定は簡易的なため、海岸近くや湖の多い地域では誤差があります。

Tonight's score (0–100) multiplies four factors. It is a guide for comparing conditions, not a probability.

  • Geomagnetic activity: NOAA's Kp forecast is compared with the Kp needed for aurora to appear low on the horizon and overhead at your magnetic latitude. For the next two hours, a southward solar-wind Bz adds a boost.
  • Darkness: the sun's altitude is calculated on your device. The score rises once the sun is more than 5° below the horizon and is full at −16° or lower.
  • Clear sky: Open-Meteo's low, mid and high cloud are weighted into an effective cloud cover (low cloud blocks the most).
  • Moonlight: a bright moon above the horizon lowers the score a little.

Aurora can change within minutes, so use the score to decide whether it's worth heading out.

"Likely visible" on the map is a separate check: OVATION probability of 10% or more (overhead, or 60% of the highest value within 8° poleward), the sun well below the horizon, and not too much cloud right now. If OVATION is unavailable, an aurora oval estimated from Kp is used instead.

"Best spots nearby" uses hourly cloud forecasts (Open-Meteo) for 121 points about 44 km apart, within roughly ±220 km of the search point. Land points only are ranked by probability × darkness × clear sky. The land check is approximate near coasts and in lake country.