Without flash, there isn’t one perfect shutter speed that always makes falling snow visible. The key issue is contrast: snowflakes are hard to see unless they’re lit well and set against a darker background. In flat light, snow against snow or a pale sky will often just disappear.

If you want distinct flakes without flash, your best chance is bright light on the flakes with a shaded or darker background behind them. A faster shutter speed can help reduce streaking, but whether flakes show up at all still depends heavily on lighting and background.

Flash is usually the most effective way to make flakes stand out, especially if it’s near the lens axis, but if you prefer not to use it, look for natural situations that create separation—sunlit snowfall, darker trees or buildings behind the snow, and moments when the snow is just starting so the whole scene isn’t already white.

Also, don’t focus only on isolated flakes: snowy weather often works best when it supports the overall scene rather than becoming the only subject. Take lots of frames, experiment, and enjoy the conditions while you have them.