Cavan borders six counties:
Leitrim to the west,
Fermanagh to the north,
Monaghan to the north-east,
Meath to the south-east,
Longford to the south-west and
Westmeath to the south. Cavan shares a border with
County Fermanagh in
Northern Ireland. Cavan is the 19th largest of the 32 counties in area and the 25th largest by population. The county is part of the
Northern and Western Region, a
NUTS II area, and in that region, is part of the
Border strategic planning area, a NUTS III entity. The county is characterised by
drumlin countryside dotted with many lakes and hills. The north-western area of the county is sparsely populated and mountainous. The Cuilcagh mountain range contain the highest point,
Cuilcagh, at . Cavan is the source of many rivers.
Shannon Pot on the slopes of Cuilcagh is the source of the
River Shannon, the longest river in Ireland at . The
River Erne is a major river which rises from Beaghy Lough, two miles (3 km) south of
Stradone in Cavan and flows for to
Lough Erne. Other rivers in the county include the
Blackwater River, which rises near Bailieborough and flows through
Lough Ramor, joining the
River Boyne at Navan;
the Dee which springs near
Bailieborough; the
River Annalee which flows from
Lough Sillan and joins the Erne; and the
Cladagh river which rises from Cuilcagh and flows into
Fermanagh. The
Glyde and the
Owenroe also source in Cavan. Cavan is known as 'The Lakeland County' and is reputed to contain 365 lakes. A 2021 book by local photographer Hu O'Reilly listed and photographed the 365 lakes. At ,
Lough Sheelin is the county's largest lake; it is situated in the south of the county and forms a three way border on its waters between counties Meath, Westmeath and Cavan. A large complex of lakes form in the north and west of Cavan into designated Specially Protected Areas (SPA); an example is
Lough Oughter. Other important wildlife protected lakes such as
Lough Gowna and
Lough Ramor are in the south and east of the county. Cavan has a mainly hilly (drumlin) landscape and contains just under of forested area, 3.6% of Cavan's total land area. The county contains forests such as Bellamont Forest near
Cootehill,
Killykeen Forest Park at Lough Oughter (a Coillte state forest concern),
Dún na Rí Forest Park and the Burren Forest.
Climate Met Éireann records the climate data for Cavan from their station at
Ballyhaise. Under
Köppen climate classification, Cavan experiences a maritime
temperate oceanic climate with cold winters, mild humid summers, and a lack of temperature extremes. The average maximum January temperature is , while the average maximum July temperature is . On average, the sunniest months are May and June, while the wettest month is October with of rain, and the driest months are May and June with and respectively. Humidity is high year round and rainfall is evenly distributed throughout the year, with the annual precipitation at Ballyhaise being On average, snow showers occur between November and March. In the winter of 2010–11, record low temperatures for November, December and January were recorded in Cavan. In late December, the temperature at the station fell to , its lowest ever. On 21 December 2010, a daily maximum of was recorded at Ballyhaise, the lowest daily maximum ever recorded in Ireland. Summer daytime temperatures range between and , with temperatures rarely going beyond . The average annual sunshine hours range between 1,300 hours in the north to 1,500 hours in the south. ==Subdivisions==