Projecting climate-driven changes in marine systems will require knowledge on how thermal windows affect the vital rates of key species. To examine the potential, direct effect of climate-driven warming on southwest Baltic herring, we quantified the survival, development, and biochemical condition of embryos (eggs and yolk-sac larvae) at ten temperatures between 2.9 and 21.7°C. Viable hatch was highest from 7 to 13°C, 160°d post-hatch. RNADNA ratios rapidly decreased between 50 and 80°d post-hatch, whereas DNA ×DM -1 increased throughout the yolk-sac phase and likely provides a stronger indicator of irreversible starvation. The critical, "mixed feeding" stage is likely 60100°d post-hatch. The broad thermal tolerance of herring embryos makes "direct", negative effects of warming unlikely; however, a lack of common methods among studies makes it difficult to project how climate warming will affect embryos of different fish populations and species.