Summary statement The role of Nonsense‐mediated decay (NMD) in exercising quality control over RNAs produced following heat stress was analysed using NMD‐compromised mutants, and the degradation of potential NMD targets was demonstrated, as well as their roles in plant thermotolerance. Heat increases the frequency of alternative splicing, and the production of nonproductive RNA transcripts creates a challenge for thermotolerance that is met by NMD.