Summer Driving Tips Ireland: How to Keep Your Car Cool and Safe

The Irish summer reality

Average Irish summer temperatures (15–22°C) don't sound extreme by any global standard. But the 2018, 2022 and 2025 heatwaves all pushed past 30°C, and the long-term Met Éireann data shows higher peaks becoming more common. Cars don't need 40°C to suffer in summer — even moderate sustained heat (20–25°C) puts real strain on:

• Cooling systems that may have been quietly degrading through winter
• Tyres whose pressure rises noticeably with ambient temperature
• Batteries that lose water and corrode faster in heat than in cold
• Air conditioning systems that haven't been used since last September
• Engine oil and brake fluid that thin and lose effectiveness at high temperatures

The good news: an hour of preparation before the first warm spell prevents almost every summer breakdown. This guide walks the six issues that cause most warm-weather AA call-outs in Ireland and the practical fixes for each.

Issue 1 — Overheating (the #1 summer breakdown cause)

AA Ireland reports overheating as one of the most common warm-weather call-outs every summer. Common causes:

• Low coolant level (loss through evaporation, leaks, or never topped up)
• Leaking hoses (cracked, swollen, or chafed against engine components)
• Broken electric cooling fans (won't kick in when stopped in traffic)
• Blocked radiators (clogged with debris, dead bugs, leaves)
• Failing thermostats (stuck closed = overheating; stuck open = poor heater performance)

Warning signs

• Temperature gauge climbing above normal
• Steam from under the bonnet
• Coolant smell — sweet, slightly chemical
• Power loss
• Coolant warning light (often a thermometer with wavy lines) — see our Dashboard Warning Lights guide

What to do if your car overheats

1. Pull over immediately in a safe spot
2. Turn OFF the air conditioning (it loads the engine)
3. Turn the heater fan ON to maximum — counter-intuitive but it pulls heat from the engine into the cabin
4. If the engine is still running, drive at low revs to the nearest safe stopping place
5. Once stopped, switch off the engine
6. Wait at least 30 minutes before opening the bonnet — pressurised hot coolant can cause severe scalding burns
7. NEVER open the radiator or expansion-tank cap when hot — wait until the engine is cool to the touch
8. Check coolant level in the expansion tank (between min and max marks)
9. Top up with proper coolant (water in absolute emergency only — but proper coolant is far better)
10. Drive directly to a garage — don't continue your normal journey

See our Car Breakdown in Ireland guide for AA / RAC / IRR numbers, motorway and rural procedures, and what your insurance breakdown cover does and doesn't include.

Overheating — prevention checklist

• Check coolant level monthly in summer (between min and max on the expansion tank)
• Inspect coolant hoses for cracks, swelling, leaks — under the bonnet, with the engine cold
• Get a cooling-system pressure test annually (€20–€40 at most garages)
• Replace coolant per manufacturer schedule (typically every 5 years or 100,000 km — see our How Often to Service guide for context)
• Listen for unusual cooling-fan behaviour — constantly running, never running, intermittent
• Watch the temperature gauge — most cars sit centred most of the time; any drift up is worth investigating

Issue 2 — Tyres in heat

Air inside tyres expands with heat. Pressure rises ~1 PSI per 5.5°C (10°F) ambient temperature increase. A tyre at 35 PSI on a cold January morning could be 42–45 PSI on a hot afternoon motorway run — combined with worn tyres, sidewall cuts, or bulges that's real blowout risk.

Pre-summer tyre checklist

• Tread depth: legal minimum 1.6 mm; recommended 3 mm+. See our Car Tyres in Ireland guide
• Inspect sidewalls for cracks, bulges, cuts
• Check pressures when COLD (before driving) using your manufacturer's specified PSI — door-jamb sticker or fuel cap, NOT the maximum number on the tyre sidewall
• Don't release pressure on hot tyres — they'll be underinflated when cold
• Check the spare too (often forgotten — and the moment you need it, it'll be flat)
• Tyre age: replace tyres over 6 years old regardless of tread (rubber degrades; sidewalls develop micro-cracks not visible from outside)

Summer-specific tyre tips

• Park in shade where possible — hot tarmac plus UV degrade rubber faster
• For long high-speed motorway journeys, glance at pressures at fuel stops (within reason — don't release hot pressure)
• Watch for unusual vibration — could indicate a developing tyre problem
• Towing or carrying a heavy load: increase pressures per the “heavy load” recommendation in your handbook

Issue 3 — Battery (heat is worse than cold)

Counter-intuitive but well-established: high heat is more damaging to lead-acid batteries than cold. Heat accelerates internal corrosion and water loss in flooded batteries; cold simply makes them less efficient at delivering current. Most car batteries last 4–6 years in Irish conditions; heatwave summers shorten the upper end of that range.

Signs of a tired battery

• Slow cranking on hot mornings
• Dashboard lights flickering
• Electrical accessories acting strange
• Battery 4+ years old

What to do

• Get the battery tested at any AA service or garage (often free)
• Replace before it fails — much cheaper than a roadside breakdown
• Cost: €80–€150 fitted for a typical car battery

For EV traction-battery health (a separate topic), see our EV Battery Replacement guide.

Issue 4 — Air conditioning

Re-gassing

AC systems lose refrigerant gradually through normal seal permeability. If your AC isn't as cold as it used to be, it likely needs a re-gas — typically €80–€150 at a specialist or general garage with AC equipment. Worth doing in spring before the first warm weekend.

Daily-use AC tips

• Use recirculation mode after the initial cool-down — more efficient, keeps cool air in
• Don't open windows AND use AC simultaneously — wastes fuel
• Park in shade or use a windscreen sunshade — reduces interior temperature by 10–15°C, makes AC's job vastly easier
• In stop-start traffic, switching off AC for short periods reduces engine load (modern cars manage this automatically with start-stop systems)

Faulty AC isn't just uncomfortable — it causes driver fatigue, which is a real safety issue on long summer drives.

Issue 5 — Sun glare

Low morning and evening sun on east-west Irish routes can be temporarily blinding, especially after rain when the road surface acts as a mirror. Practical defences:

• Keep the windscreen INTERIOR clean — dirty inside glass scatters light dramatically. Most drivers never clean the inside; it's the single biggest cheap improvement
• Quality polarised sunglasses — cut glare more than tinted lenses
• Use the sun visor early and decisively — don't wait until you're dazzled
• Slow down — perception time is reduced when dazzled
• Increase following distance dramatically in bad glare
• If glare is genuinely dangerous, pull over until the sun moves — five minutes is cheaper than a rear-end collision

Issue 6 — Fluids degrade in heat

• Engine oil: thin oil + heat = less lubrication margin. If you're due a service, do it before summer rather than after
• Brake fluid: absorbs moisture over time; high temperatures during sustained or hard braking can cause brake fluid to boil (vapour lock = no brakes momentarily). Replace per manufacturer schedule (typically 2 years)
• Power steering fluid: check level, top up if low
• Screen wash: top up — lots of bug splatter and pollen in summer; an empty reservoir on a smeared windscreen is a real visibility hazard
• Coolant: covered in the overheating section above — the most important summer fluid

Long-journey holiday checklist

• 1 week before: check all fluids, tyres, lights, battery
• 2 days before: tyre pressures (cold), spare-tyre check, clean windscreen inside and out
• Day of: emergency kit (water, snacks, phone charger, basic toolkit, first aid, high-vis vest)
• For cross-border or European trips: warning triangle, jumper cables, medical kit (some EU countries require these). For Northern Ireland specifically, see our Driving in Northern Ireland from the Republic guide
• Plan fuel stops — long Wild Atlantic Way / Ring of Kerry / Connemara loops have fewer filling stations than you expect

Children and pets in summer cars — never leave them

EVs in summer

• Modern EVs have active liquid battery thermal management — they handle heat well
• Avoid leaving an EV at 100% charge in hot weather — the battery prefers being stored at 60–80% state of charge
• Pre-cool the cabin while plugged in — uses grid power, not battery
• Hot weather can reduce EV range by 5–15% (cabin cooling load, not battery failure)
• Avoid repeated DC fast-charging in extreme heat — compounds heat stress on the cells
• For the full long-term battery picture (degradation rates, replacement costs, when to worry), see our EV Battery Replacement guide

Ireland's overall mild Atlantic climate is genuinely favourable for EV battery longevity — heat is the biggest battery killer globally and we have very little of it by international standards.

Irish-specific summer concerns

• Sudden weather changes: an Irish summer day can swing from 20°C to 8°C in hours. Carry a light jacket regardless of the morning forecast
• Long daylight hours: drivers fatigue from extended driving — take breaks every 2 hours, even on familiar routes
• Tourist traffic: Wild Atlantic Way, Ring of Kerry, Connemara and the Causeway Coastal Route become congested with international visitors and Irish staycationers. Plan extra time and avoid peak weekends if you can
• Pothole damage: spring rains followed by hot summer baking expand existing potholes. Watch road surfaces, especially on rural routes
• Pollen and bug splatter: top up screen wash, keep wipers in good condition
• Festivals + Garda checkpoints: more roadside checks during summer events (Electric Picnic etc.) — see our Drink Driving Limits Ireland guide

What to keep in your car all summer

• 1.5 L water bottle (for cooling, drinking, top-up)
• Phone charger (in-car)
• Spare sunglasses in the glovebox
• Hand sanitiser
• Basic first-aid kit
• Sunscreen
• Tyre pressure gauge (~€10)
• Foot pump (~€20)
• Coolant top-up bottle (~€8)
• Light jacket (for the inevitable cool evening)
• High-vis vest (mandatory in some EU countries)

FAQ