Winter on the lake: how cold it gets, what heating costs, which rules apply

There is no ARPA weather station at Orta San Giulio; the most useful are Omegna, on the northern shore at 292 metres, Armeno, in the hills at 865 metres, and for comparison Borgomanero, on the plain at 300 metres³. We averaged their validated daily data over seventeen winters, from 2007/08 to 2023/24³:

The shore is milder than the plain at the same altitude: in January Omegna averages 3.8 °C with mean minimums above zero, Borgomanero 2.2 °C with mean minimums of -1.9 °C³. Over the last five measured winters Omegna had 11.6 frost days a year on average³. The coldest day in the series was 6 February 2012: -8.9 °C at Omegna, -11.3 °C at Armeno³.

The lake does not freeze. The Region's water protection plan describes Orta as a «warm monomictic» lake, with no winter stratification and up to 143 metres deep⁴; CNR measurements at the deepest point put the whole water column between 5.3 and 6.5 °C in winter⁵. None of the sources we read says it in so many words, but water at that temperature does not form an ice cover.

Snow. The nearby ARPA stations do not measure snow, and the nearest snow station is 26 km away at 1,515 metres: how many snow days the shore and the high hamlets get, we do not know.

Every Italian municipality has a climate zone, set by its degree-days: the sum, over the whole heating period, of how far each day's mean temperature is below 20 °C. Between 2,100 and 3,000 degree-days is zone E, above 3,000 zone F¹. For the thirteen lake municipalities the legal table, with the altitude of the town hall, says this (the last two columns are the calculation of the next section)¹:

What the zone means for a house²:

• zone E: heating from 15 October to 15 April, for at most 14 hours a day, also in several blocks, between 5 a.m. and 11 p.m.;
• zone F: no limits on period or hours;
• the average indoor temperature must not exceed 20 °C, with 2 °C tolerance;
• outside the season heating may be switched on only if the weather justifies it, and for no more than half the normal hours;
• the hours limit does not apply to systems serving a single home with a programmable thermostat that sets at least two temperatures over 24 hours and switches the boiler off: that covers most detached houses.

The mayor may extend or shorten heating periods and hours by order, where there is a proven need²: in a cold winter it is worth checking the municipal notice board.

The cost depends above all on the house, and a house we do not know cannot be calculated. We can, however, do a calculation with stated assumptions. The assumption: a house that loses 200 watts for each degree of difference between inside and outside, i.e. one that needs 4 kW of heating with 0 °C outside and 20 °C inside; a technician can estimate the figure for yours from its energy performance certificate. A year's heat is that loss times the degree-days times 24 hours, leaving out sunshine and the heat of the people inside, which reduce it.

At Orta San Giulio, with the legal 2,687 degree-days¹, that comes to about 12,900 kWh of heat a year. With a gas boiler of 90% efficiency and gas at 13.09 cents per kWh, the average Italian households paid, taxes included, in the second half of 2025 and the first half of 2026⁶, that is about €1,880 a year. With a heat pump giving 3 kWh of heat per kWh of electricity and power at 29.48 cents⁷, about €1,270.

Higher up costs more. The same house in Quarna Sopra needs about 16,400 kWh and €2,390 of gas, 27% more than at Orta; in Armeno 10% more. The table in the previous section gives the figure for each municipality.

Real winters have been milder than the table. The legal degree-days date from 1993. Using ARPA data for Omegna, from 15 October to 15 April over seventeen winters, we counted an average of 2,345, 13% below Omegna's legal 2,688³¹; over the last five, 2,237. With the measured winters the example house would have spent about €1,640 a year on gas.

The empty house. Keeping a house closed for the winter at 10 °C, so that pipes and walls do not freeze, costs much less: in Omegna's winters the degree-days at 10 °C were 624, 27% of those at 20 °C³, and the example house would have spent about €440 on gas.

These are not quotes: a calculation with written assumptions, for comparing municipalities and systems. Pellets and firewood are not in the calculation, because we found no price published by a public source; nor are heating oil and LPG. Which hamlets around the lake are on the mains gas network we have not verified: ask before buying a house in the hills.

Piedmont's rules for wood and pellet heaters (stoves, closed fireplaces, boilers, cooker-heaters) are read in stars, the environmental class of ministerial decree 186 of 2017. Some apply everywhere⁸⁹:

• since 1 October 2019 only appliances rated 4 stars or more may be installed, in every municipality of the region; the regional air quality plan extends the ban to wood or pellet cooker-heaters and cookers not used only for cooking;
• wood and pellet systems, new or existing, must be entered in the register of heating systems;
• pellet stoves below 35 kW may only burn pellets certified class A1 (standard UNI EN ISO 17225-2), and the paperwork must be kept.

Others depend on the municipality's air quality zone. In the regional list in force, Ameno, Bolzano Novarese, Gozzano, Omegna, Pettenasco and San Maurizio d'Opaglio are in the «Hill» zone; Armeno, Madonna del Sasso, Miasino, Nonio, Orta San Giulio, Pella and Quarna Sopra in the «Mountain» zone¹¹. In the hill municipalities, on top⁸¹²:

• a ban on using appliances below 3 stars, unless a stove below 35 kW is the only heating in the house;
• from 15 September to 15 April the smog alert: ARPA checks on Mondays, Wednesdays and Fridays, and turns it orange when it forecasts PM10 above 50 micrograms per cubic metre for three days, red above 75.

Under orange or red, the Region's model order bans wood stoves and fireplaces below 5 stars if the house has another heating system, lowers the average temperature in homes to 18 °C (plus 2 tolerance) and bans any fire in the open, barbecues and bonfires included¹³¹⁵. Omegna is also among the 76 Piedmont municipalities with traffic restrictions¹⁴. Each municipality applies the measures with its own order, which may be stricter¹².

What is changing. The update to the regional plan approved by the Council on 28 July 2026 provides, from 1 August 2027, for a ban on installing wood or pellet appliances below 35 kW with fewer than 5 stars¹⁰. It is a plan action: we have not yet found the act that makes it binding. Anyone replacing a stove today would do well to look at 5 stars.

Burning grass cuttings and prunings in small heaps in the garden is allowed only at certain times, and here too the air zone matters¹⁵:

• in the hill municipalities (Ameno, Bolzano Novarese, Gozzano, Omegna, Pettenasco and San Maurizio d'Opaglio) it is banned from 15 September to 15 April and in July and August, and always on orange or red alert days;
• in the mountain municipalities (Armeno, Madonna del Sasso, Miasino, Nonio, Orta San Giulio, Pella and Quarna Sopra) it is banned from 1 November to 31 March;
• everywhere it is banned during the periods of highest forest-fire risk declared by the Region.

The Highway Code lets whoever manages a road require winter tyres or chains on board; a directive of the Ministry of Infrastructure sets the period for everyone from 15 November to 15 April, except for roads with particular conditions¹⁶¹⁷.

Novara provincial roads. An order of the Province, written for the period from 15 November to 15 April «of every year», requires winter tyres or chains on board on its whole network; the obligation also applies outside the period when it snows or there is ice, and motorbikes and mopeds may only ride with no snow or ice¹⁸. The roads on its list include those of the lake: the western lake road (SP 46), Lagna–Pella (SP 48) and the branch to Alzo, Madonna del Sasso (SP 49), Armeno–Omegna (SP 42), Miasino–Ameno–Bolzano Novarese (SP 43), the Pettenasco road (SP 127), the Mottarone road (SP 41) and the roads to Gozzano¹⁸.

State road 229 «del Lago d'Orta». In winter 2025/26 the obligation applied from 15 November to 15 April from km 33.200 to 60.489, that is from Borgomanero to Gravellona Toce, and on the Borgomanero bypass¹⁹²⁰. ANAS had not yet published the 2026/27 list on 31 October 2026.

The provincial roads on the Verbano-Cusio-Ossola side (Quarna, Nonio, the Omegna slope) belong to another Province, whose order we could not read: if you drive up to Quarna Sopra in winter, keep chains on board anyway.

• Sacro Monte di Orta: from 25 October 2026 to 27 March 2027 the chapels are open from 9:30 to 16:00 on weekdays and until 16:30 on Saturdays, Sundays and holidays; the church every day from 9:00 to 18:00. Parking is free from 15 to 31 December, and in January and February you pay only at weekends and on holidays²¹.
• Orta San Giulio tourist office: from 1 November to 20 December 2026 open only on Saturdays and Sundays, 10:30–13:00 and 14:00–16:00²².
• The island: there are no scheduled boats in winter (timetables in the guide Getting here). A consortium of water taxis in Orta states on its website a service between Orta and the Isola di San Giulio «in every period of the year», without publishing winter times or fares²³.

A lake house closed from November to March keeps on costing: the minimum heating to stop it freezing (in the example, about €440 of gas at 10 °C), IMU, which on a second home is due regardless (the guide IMU property tax on the lake has the rates), fixed utility charges and checks. A house lived in during the winter too, by you or by tenants, stays warmer and deteriorates less.

Are you thinking of letting your lake house outside the season too, or of selling it? The guide Renting out your lake home explains the rules; the tool From price to net shows what a sale leaves you; if you would like our view on your house, tell us about it.