The last frost in Ystradgynlais, Wales was the night of the Friday 26/02/2021 to Saturday 27/02/2021, with a minimum air temperature of 2.0°C (35.6°F), and therefore a probable minimum ground temperature of around -1.0°C (30.2°F).
There are no frosts forecast for Ystradgynlais in the next 5-days.