Objective:

To examine associations between daily weather conditions and unscheduled mental health–related healthcare contacts in England using large-scale national surveillance data.

Approach:

• Study Design: Retrospective observational study across nine English regions from 1 January 2014 to 31 December 2022.
• Data Sources: Daily anonymised and aggregated healthcare contact data from NHS 111, GP out-of-hours services, and emergency departments.
• Weather Exposures: Mean daily temperature, hours of full sunshine, and total daily rainfall.
• Statistical Analysis: Distributed lag non-linear models at regional level, combined through two-stage multivariate meta-analysis, adjusted for seasonality, long-term trends, day of week, public holidays, and population size.

Key Findings:

• Mental health–related unscheduled healthcare contacts showed modest but consistent associations with temperature and sunshine.
• Relative risks increased with rising temperatures up to around 18 °C and were higher on days with fewer hours of sunshine.
• Sunshine demonstrated the clearest pattern, with increased utilisation on low-sunshine days across all healthcare settings.
• Rainfall was not consistently associated with healthcare contacts.
• Age-stratified analyses indicated a U-shaped relationship between temperature and ED attendances among adults aged over 64 years, with higher utilisation during both colder and warmer conditions.

Interpretation:

Short-term variations in temperature and sunshine are associated with changes in unscheduled mental health–related healthcare utilisation, while rainfall shows little consistent effect.

Limitations:

• Effect sizes were modest, typically within ±10–20% of baseline levels.
• Limited evidence on the impact of day-to-day variations in typical weather conditions on mental health outcomes.

Conclusion:

Findings highlight the role of everyday weather conditions in influencing mental health–related healthcare demand.