Cairngorms Midges in May — Risk, Peak Times, Kit
Background pressure only. Head net optional. Subarctic plateau and dry continental climate keep the high tops nearly midge-free even in peak season. The wooded glens and Spey valley are a different story — sheltered, damp, and as bad as anywhere east of the watershed.
Current risk
Cairngorms in May: Low. Background pressure only. Head net optional.
When they bite
Peak biting windows are dawn 6–8am and dusk 5–7pm. First proper warmth arrives in the Spey valley, with afternoon highs into the mid-teens. The plateau lags by 5-10°C. Ground temperatures rise enough to trigger the first midge hatches in low sheltered glens by the second half of the month.
What to wear
- Smidge repellent (75ml)
- Light-coloured long-sleeve baselayer — midges have a strong preference for dark clothing.
Tactical notes
May is the transition month. The first generation of midges hatches in sheltered low-elevation spots — typically the second half of May — but the hatches are small and patchy and most Cairngorms trips this month encounter nothing. The high plateau (anything above about 600m) remains effectively midge-free even at the end of the month.
Where you'll first notice them: the [Glen Feshie](/glens/glen-feshie) pine forest at dusk, the southern fringes of Rothiemurchus, the marshy ground around Insh and the lower Spey banks. These are the warmest, dampest, most sheltered habitats in the region and they fire first. By the end of May an evening barbecue by [Loch Morlich](/wild-swimming/loch-morlich) is plausible without a head net but possible to have your evening spoiled if the wind drops to nothing under cloud cover.
For planning: don't change a Cairngorms May itinerary based on midges. Carry Smidge as insurance — it weighs nothing and you'll be glad of it if you hit a sheltered glen on a still warm evening. A head net is overkill for May trips above 500m but worth packing for low-glen camps at Achlean, Glenmore, or the Linn of Dee. Most Munros are still genuinely midge-free this month even at the bothy stage at the start of the day — [Carn a' Mhaim](/hillwalking/munros/carn-a-mhaim), [Derry Cairngorm](/hillwalking/munros/derry-cairngorm), [Beinn a' Bhuird](/hillwalking/munros/beinn-a-bhuird-beinn-a-bhuird-north-top) are all early-summer routes that escape the pressure entirely.
The rule of thumb: above the treeline in May, no midges. Below the treeline at dawn or dusk, possible.