There is evidence of some large fires being started by landowners who wish to clear land outside the permitted burning season, which in upland areas ends on 31 March.
Mae'r dystiolaeth yn dangos bod rhai tanau mawr yn cael eu cychwyn gan berchnogion tir sy'n awyddus i glirio tir y tu allan i'r tymor llosgi pan ganiateir iddynt wneud hynny.