Anga & Seemanchal · Middle & Lower Gangetic Plain
Terrain and eco-zones
Humid subtropical, wetter than the rest of Bihar and wetter still towards Kishanganj, where annual rainfall exceeds 2,000 mm — the highest in the state, and a direct consequence of the funnel between the Himalaya and the Rajmahal hills. Humidity is high through most of the year; January nights fall to 8–10 °C and May reaches 40 °C.
Landforms
Ganga floodplain, with the river at its widest and most braided before it turns south at RajmahalKharagpur and Rajmahal hill approaches in the south — the plateau's last outcropsKosi and Mahananda floodplain, waterlogged and re-cut annuallyDiara — the sandy mid-river land, farmed between floodsTerai foothill and tea land in the Kishanganj neck
Rivers and waters
Ganga — wide, dolphin-bearing, and the region's axisKosi — arriving from the north-west and joining the Ganga at KurselaMahananda — the eastern river, shared with BengalChandan, Badua and Kiul, coming down from the southern hillsGhaghri, Kankai and Donk in the border belt
Through the year
| Season | Months | Typical | What it is like |
|---|---|---|---|
| Winter | November–February | 8–24 °C | Cool and foggy, with the makhana and maize markets busy and the tea gardens dormant. The best months for the Ganga and the dolphin stretch. |
| Summer | March–June | 25–40 °C | Humid rather than dry. Zardalu mangoes from late May, and the litchi and jackfruit season across the belt. |
| Monsoon | July–September | 27–34 °C | Very heavy, and the Kosi and Mahananda flood most years. The Shravani Mela runs through it, with pilgrims walking a soaked road for a month. |
| Post-monsoon | October | 22–32 °C | Durga Puja, and the water draining slowly off the interfluve. |
Best time to visitNovember to February for the river, the silk town and Seemanchal. Sawan, in July and August, if the point is the Sultanganj-to-Deoghar kanwar walk, which is the largest thing that happens here.
The climate, landforms, rivers and seasons of Anga & Seemanchal, and the best time of year to visit. (4)