New York City Mayoral Primary, 24 June 2025

Heatwave 

On 24 June 2025, New York City held its Democratic Party mayoral primary amidst an intense early summer heatwave. Temperatures soared to 39 °C (102 °F) at JFK Airport and 37 °C (99 °F) in Central Park, making it one of the hottest June days on record in the city (Small 2025). The National Weather Service issued an extreme heat warning, advising residents, particularly the elderly, chronically ill and those without access to air conditioning, to limit outdoor activity (Fawcett 2025). Despite the conditions, nearly one million ballots were cast. Of these more than 380,000 were via early voting, a significant increase from the last mayoral primary (Coltin and Anuta 2025; Brosnan 2025). Voters used a ranked-choice voting system and Zohran Mamdani won the nomination with 56 per cent of the vote in the final round (NBC/Caruso 2025). 

Impact on the electoral process 

The extreme heat directly affected voters and polling infrastructure across the city. In-person voting remained open during regular hours, but candidates, elected officials, and public health advocates raised concerns about the risks faced by voters, especially vulnerable groups. Two Democrat politicians within New York State issued a joint statement four days beforehand criticizing the New York City Board of Elections (BOE) for lacking sufficient heat-related contingency plans (Small 2025).  

No legal changes were enacted in response to the heatwave. However, the BOE implemented several short-term procedural adjustments to address public health risks on election day. These included the distribution of water and portable fans at polling sites, as well as coordinating with emergency utility providers to ensure a stable power supply at all polling locations (NYC Board of Elections 2025). There were also reports of emergency services parking a bus outside a polling station for poll workers to cool off during breaks (McCarthy et al. 2025). 

Isolated incidents of equipment malfunction were reported, as minor technical issues arose due to the heat, such as the humidity causing “ballots to stick together” and “signal issues with scanners” at certain polling sites (McCarthy et al. 2025).  

Despite these challenges, the election proceeded as scheduled. Over 546,000 in‑person votes were cast on election day (McCarthy et al. 2025). Final count rounds brought total ballots to 1,026,783, marking the highest turnout in a mayoral primary since 1989 (Coltin and Anuta 2025). This turnout was notable given the extreme weather conditions, although some observers suggested that the heatwave may have discouraged participation among elderly or medically vulnerable voters (Coltin 2025). According to political reporting, this may have had an impact on former Governor Andrew Cuomo’s performance, as his voter base was perceived to include a higher proportion of older constituents (Coltin 2025).