Northumbrian dialect or Northumbrian and Durham dialect is any one of several traditional English dialects spoken in the historic counties of Northumberland and County Durham. The term Northumbrian can refer to the region of Northumbria but can also refer specifically to the county of Northumberland. This article focuses on the former definition and thus includes varieties from throughout the wider region, including County Durham.

The traditional Northumbrian dialect is a moribund older form of the dialect spoken in the area. It is closely related to Scots and Cumbrian and shares with them a common origin in Old Northumbrian.

The traditional dialect has spawned multiple modern varieties, and Northumbrian dialect can also be used to broadly include all of them:

Alexander John Ellis, a 19th century linguist and philologist, divided Northumberland and Durham into three main dialect groups based on their linguistic features. Ellis considered the bulk of Northumberland and northern County Durham as belonging to the 'North Northern' dialect group. This group was deemed to be a transitional variety between other Northern dialects (those north of the Humber–Lune Line) and Scots, but overall still considered a form of Northern English. However, a small portion of northwestern Northumberland around the Cheviot hills was deemed to be Scots-speaking and therefore categorised as a variety of the Scots language. The southern part of County Durham was considered part of the 'West Northern' dialect group, which was deemed to be more closely related to Richmondshire and Cumbrian dialects, especially that of the Vale of Eden. Like Cumbrian, the dialect of south Durham was subject to greater Scandinavian influence than the rest of Durham and Northumberland. Scandinavian influence is evident in the naming of streams in south Durham, which are typically named ‘becks’ (from the Old Norse ‘bekkr’). In contrast, 'burns' (from the Old English ‘burna’) are found in north Durham and Northumberland.

Urban North East English dialects are a group of English dialects spoken in urban areas of the North East of England, including major cities such as Newcastle upon Tyne, Sunderland, and Middlesbrough. These dialects have emerged as a result of the region's rapid urbanization during the 19th and 20th centuries, which brought about significant social and demographic changes. In comparison to traditional dialects, urban North East English dialects have undergone a greater degree of dialect levelling. A tripartite division is recognised among modern urban dialects in the North East of England, which distinguishes between the northern, central, and southern urban dialects:

Central and northern urban dialects retain a decidedly Northumbrian base, but have been shaped by a standard English superstrate, resulting in hybrid dialects that incorporate elements of both traditional dialects and more standardised forms of English. On the other hand, the southern urban dialects have been subject to more significant dialect restructuring, resulting in a dialect which, while still North Eastern in character, lacks more marked Northumbrian forms such as 'gan' (to go) and 'divvent' or 'dinnet' (don't) that survive in Tyneside, Wearside and Durham.

Berwick-upon-Tweed is unique within Northumberland. The local speech has characteristics of the North Northumbrian dialect and due to its geographical location, has characteristics of the East Central Scots dialect as well.

A sociological study of the Anglo-Scottish border region conducted in the year 2000 found that locals of Alnwick, 30 miles (48 km) south of Berwick, associated the Berwick accent with Scottish influence. Conversely, those from Eyemouth, Scotland, 9 miles (14 km) north of Berwick, firmly classed Berwick speech as English, identifying it as Northumbrian.