From the benchWith rain and snow showers hammering the Firehole all day and temps struggling to hit 48°F, don't expect a classic afternoon hatch — instead, focus your dry-fly time in the 10 AM to 1 PM window when any brief clearing will trigger a compressed BWO or midge flurry on the flat meadow sections near Fountain Flats. For the rest of the day, go subsurface: rig a tungsten nymph like the Juju Baetis or Split Case PMD under a small indicator and dead-drift through the inside seams at 18–24 inches — the Firehole's geothermally warmed water keeps fish active even when the air is miserable. If you want to cover water efficiently, swing a soft hackle through the riffles on a tight line; the cold front will push fish to feed aggressively between storm cells.