mn_newbee · Minnesota, US · Beginners · Nov 2, 2026

Upper entrance for winter in Minnesota — do I really need one if the bottom entrance has a reducer?

First winter with two Langstroth 10-frame hives here in central Minnesota. Day temps are sitting around 3°C now and nights are well below freezing. My local association is totally split on upper entrances. One half says drilling an auger hole in the top deep or flipping the inner cover notch down is vital so damp air can escape when snow drifts bury the bottom entrance. The other half insists upper ventilation just creates a chimney effect that pulls warm air right off the cluster, forcing them to burn through stores twice as fast. Both hives have 40 mm foam insulation under the outer cover and entrance reducers on the bottom set to the small notch. If heavy snow blocks the bottom board, will they really suffocate without that top hole, or am I chilling the cluster for nothing?

#winter-prep#ventilation#upper-entrance#minnesota

▲ 3 votes 💬 4 replies ✅ Solved

4 replies

QuebecBees · Nov 2, 2026

Up here in Quebec we get massive snow cover. An upper escape is essential, but you don't want a howling gale. Use an inner cover rim notch (about 8 mm by 25 mm) rather than an open auger hole. Snow WILL cover your lower entrance for weeks at 45°N.

ImkerinLena · Nov 2, 2026 · ✅ Accepted answer

The thermodynamic argument against chimney draft is real, @mn_newbee. If you run top insulation with high R-value (R-10+) and ensure the ceiling is warmer than the walls, moisture condenses on the cold side walls, not on the bees. A small notch under the lid is insurance, but don't over-ventilate.

VTBeeHannah · Nov 2, 2026

I saw bottom entrances completely slush-locked in Vermont two seasons back. Lost one hive because dead bees blocked the tiny bottom notch from the inside. That small upper notch gives them a way out for cleansing flights on 8°C days too.

mn_newbee · Nov 2, 2026

Thanks @ImkerinLena and @QuebecBees. That distinction between a top vent and a full-blown chimney makes total sense. I'll stick with a single tiny notch under the insulated lid rather than boring holes through the boxes.

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