Autumn packing, Sep to Oct
Autumn, September, October
The weather shifts quickly in autumn. September can still feel like late summer some days, but October is firmly cold and wet. Go back to the thicker mid layer and make sure your jacket is properly waterproof, not just water resistant. Wind picks up and daylight drops fast.
Key extras: Thicker fleece or light down jacket, waterproof pants, wool socks, a warm hat for October. Northern Lights season begins in September, pack dark clothing and a tripod if you want to photograph them. Daylight drops from 14 hours in September to 9 hours by late October.
Winter, November, December, January, February
Go warmer on every layer. A thicker mid layer, proper thermal base, and don't skip the wool socks. Hand warmers make a genuine difference on cold days. Shoe cleats are worth packing since black ice on sidewalks is common and easy to miss. A reflective clip or band is important because it gets dark early and drivers need to see you.
Key extras: Warm hat, scarf or buff, waterproof insulated gloves (bring a spare pair, they get wet at waterfalls), merino thermal base top and bottoms, thick fleece mid layer, wool socks (at least 3 pairs), shoe cleats, hand warmers, reflective clip or band. Temperatures range from −5°C to 5°C, but wind chill can make it feel much colder.
Spring, March, April, May
March is still winter in practice. Expect snow, ice, and serious wind. April is the most unpredictable month, you can get sunshine, sleet, and horizontal rain in the same afternoon. By May things ease up, but it's not warm. Keep the waterproof shell, bring a medium fleece, and don't ditch the wool socks yet. Shoe cleats are still useful in March and sometimes April.
Key extras: Medium weight fleece, waterproof pants for hikes, wool socks, shoe cleats (March to April), sunglasses (daylight increases rapidly in April and May, up to 17 to 20 hours). Pack layers you can add and remove quickly, you may do it five times in a single day.
Summer, June, July, August
Here's the part most packing lists get wrong: Icelandic summer can feel like real summer. On a warm, still day in July or August, 14°C to 16°C in direct sun with no wind is genuinely pleasant. You can walk around Reykjavík in a light dress, a t-shirt, or linen trousers and feel perfectly comfortable. Locals do this all the time. The catch is wind. If the wind picks up, that same temperature feels completely different. Pack your summer clothes, but keep a proper windproof jacket in your day bag. The weather can turn in ten minutes, and the jacket is what lets you enjoy the rest of the day instead of cutting it short.
Key extras: Eye mask for sleeping (midnight sun means near 24 hour daylight), sunscreen SPF 30+, light rain shell, shorts or light hiking pants for warmer days, a summer dress or light outfit for calm days in town, bug spray if visiting the highlands (midges appear in sheltered areas). Temperatures range from 8°C to 15°C, occasionally higher on still days.