When does the March Brown hatch?

The March Brown typically runs for 4 weeks. Peak emergence occurs in the afternoon.

What water temperature triggers the March Brown hatch?

The March Brown hatches when water temperature is between 55°F and 65°F, with peak activity around 60°F.

March Brown Parachute #10-12, Grey Fox Comparadun #12, March Brown Nymph #12.

Hatch profile

Maccaffertium vicarium

MayflyAfternoon

Water-temperature trigger

30°F55–65°Fpeak 60°F80°F

Top fly patterns

Sporadic emergence rather than a heavy hatch — but trout key on individual large duns drifting through. Freestone-river specialty.

Best rivers

Bield Fish watches USGS water-temp gauges for your home water and pings you when conditions hit the 55–65°F trigger window.