South Witham is bisected by the River Witham, about 3 miles (4.8 km) to the east of its source.
It is the point on the A1 where it enters Lincolnshire from the south, near The Fox Inn.
The parish of 1,770 acres (7 km²)  acres borders Thistleton and Rutland to the south, and the boundary to the west meets Wymondham, Leicestershire at Thistleton Gap.
The parish includes the Forty Acre Wood to the north-west, where it borders Gunby.
The boundary goes due east to meet North Witham parish at the first undulation in the road northwards.

Crossing the road, the boundary goes due eastwards to meet the A1, which it then follows due south on the east side of the road.
The boundary goes through The Fox, with North Witham parish to the east, to a point just south of the A1 interchange.
The A1 was upgraded in early August 1971, through Rutland, to Tickencote (built by Rutland County Council).
Before the road was improved, the South Witham crossroads on the A1 lay at the point where the sliproads join today.

Nearby to the south was RAF Cottesmore, and the village was the centre of the flight path circuit.
South Witham is bisected by the River Witham, about 3 miles (4.8 km) to the east of its source. It is the point on the A1 where it enters Lincolnshire from the south, near The Fox Inn. The parish of 1,770 acres (7 km²)  acres borders Thistleton and Rutland to the south, and the boundary to the west meets Wymondham, Leicestershire at Thistleton Gap. The parish includes the Forty Acre Wood to the north-west, where it borders Gunby. The boundary goes due east to meet North Witham parish at the first undulation in the road northwards.
Crossing the road, the boundary goes due eastwards to meet the A1, which it then follows due south on the east side of the road. The boundary goes through The Fox, with North Witham parish to the east, to a point just south of the A1 interchange. The A1 was upgraded in early August 1971, through Rutland, to Tickencote (built by Rutland County Council). Before the road was improved, the South Witham crossroads on the A1 lay at the point where the sliproads join today.
Nearby to the south was RAF Cottesmore, and the village was the centre of the flight path circuit.
South Witham