Modelling phenology to probe for trade-offs between frost and heat risk in lentil and faba bean

•Trade-off between early flowering reducing risk of heat stress at critical crop stages and frost risk.•Modelled phenological variation with sowing date and cultivar for lentil and faba bean against the climatic patterns of frost and heat.•Geographical patterns in thermal regimes emerged that were associated with latitude, altitude and continentality.•Realised warming between 1957 and 2018 shortened the time to critical stage, delayed late frost, advanced heat onset.•Dominant role of frost as the main discriminating factor among locations and main source of variation of the frost-heat window.