Isernia sits at 423 metres (1,388 feet) in the southern Apennine Mountains of Molise, giving it a climate distinct from Italy’s coastal cities. Expect warm, dry summers and cool, damp winters with some snow at higher elevations. For best time to visit information, see our best time to visit Isernia.. For things to do information, see our things to do in Isernia.. The city averages 12.5 degrees Celsius (54.5 degrees Fahrenheit) annually and receives about 910 mm of rainfall spread across the year, with November being the wettest month and July the driest.
Isernia Weather by Month: Temperature and Rainfall
| Month | Avg High (C/F) | Avg Low (C/F) | Rainfall (mm) | Rain Days | Sunshine (hrs) |
|---|---|---|---|---|---|
| January | 7 / 45 | 1 / 34 | 80 | 12 | 4 |
| February | 8 / 46 | 1 / 34 | 75 | 11 | 5 |
| March | 12 / 54 | 3 / 37 | 75 | 11 | 5 |
| April | 15 / 59 | 6 / 43 | 80 | 12 | 6 |
| May | 20 / 68 | 10 / 50 | 65 | 9 | 8 |
| June | 24 / 75 | 14 / 57 | 50 | 7 | 9 |
| July | 27 / 81 | 16 / 61 | 40 | 5 | 10 |
| August | 28 / 82 | 17 / 63 | 45 | 6 | 9 |
| September | 23 / 73 | 14 / 57 | 75 | 8 | 7 |
| October | 18 / 64 | 10 / 50 | 100 | 10 | 6 |
| November | 12 / 54 | 6 / 43 | 120 | 13 | 4 |
| December | 8 / 46 | 2 / 36 | 105 | 12 | 3 |
January and February: Coldest Months
January and February are the coldest months, with daytime highs around 7 to 8 degrees Celsius (45-46 degrees Fahrenheit) and overnight lows dropping to 1 degree Celsius (34 degrees Fahrenheit). Frost is common on clear nights and snowfall occurs 2 to 3 times per month in the city, with heavier accumulation in surrounding hilltops above 800 metres. Rainfall averages 75 to 80 mm across 11 to 12 days, making these months damp rather than dry-cold. For events and festivals information, see our events and festivals in Isernia.. For neighborhoods information, see our neighborhoods guide for Isernia.. Bring a warm coat, waterproof shoes, and layers if visiting in winter.
March and April: Spring Transition
March brings the first real warming, with highs reaching 12 degrees Celsius (54 degrees Fahrenheit) and lows of 3 degrees Celsius (37 degrees Fahrenheit). Wildflowers begin blooming in the surrounding hills by late March. April sees temperatures climb to 15 degrees Celsius (59 degrees Fahrenheit) during the day, though rain remains frequent at 80 mm across 12 days. Afternoon thunderstorms become more common as the season progresses. For where to stay information, see our where to stay in Isernia.. For travel tips information, see our Isernia travel tips.. Pack a light jacket and umbrella for spring visits.
May and June: Warming Up
May delivers pleasant conditions with highs of 20 degrees Celsius (68 degrees Fahrenheit) and lows of 10 degrees Celsius (50 degrees Fahrenheit). Rainfall drops to 65 mm across 9 days, and sunshine increases to 8 hours daily. This is one of the best months for outdoor activities in the surrounding mountains. June sees summer arrive properly: highs reach 24 degrees Celsius (75 degrees Fahrenheit), rainfall drops further to 50 mm across 7 days, and you’ll get 9 hours of daily sunshine. The nearby Abruzzo, Lazio and Molise National Park is in full green bloom.
July and August: Peak Summer, Hot and Dry
July and August are the hottest and driest months. July averages 27 degrees Celsius (81 degrees Fahrenheit) with only 40 mm of rain across 5 days with 10 hours of daily sunshine. August is marginally warmer at 28 degrees Celsius (82 degrees Fahrenheit) with 45 mm of rain. Humidity is moderate at the city’s elevation, making the heat more tolerable than in Italy’s lowland cities. Afternoon temperatures can touch 32 degrees Celsius (90 degrees Fahrenheit) during heat waves, but evenings cool to 16 to 17 degrees Celsius (61-63 degrees Fahrenheit). This is peak season for the Onion Fair and summer sagre (food festivals) in surrounding villages.
September and October: Autumn Colours and Rain
September remains warm with highs of 23 degrees Celsius (73 degrees Fahrenheit) and lows of 14 degrees Celsius (57 degrees Fahrenheit), but rainfall increases to 75 mm. Early September still feels like summer, while late September brings crisp mornings and turning leaves in the Apennine forests. October cools noticeably to 18 degrees Celsius (64 degrees Fahrenheit) during the day and 10 degrees Celsius (50 degrees Fahrenheit) at night. Rainfall is the second highest of the year at 100 mm across 10 days. The autumn foliage in the Mainarde Mountains peaks in mid to late October.
November and December: Wettest and Darkest
November is the wettest month with 120 mm of rain across 13 days and just 4 hours of daily sunshine. Highs drop to 12 degrees Celsius (54 degrees Fahrenheit) and lows to 6 degrees Celsius (43 degrees Fahrenheit). Snow becomes possible by late November at the city’s elevation. December brings highs of just 8 degrees Celsius (46 degrees Fahrenheit) with 105 mm of rain. Snow cover is common on surrounding peaks, and the city itself sees snow 2 to 4 days per month. The Christmas market in Piazza Andrea d’Isernia runs through December, bringing some warmth to the short winter days of 9 hours of daylight.
