Current forecasts from the National Weather Service and AccuWeather place Miami's overnight low for June 18 near 81°F, reflecting the dominant influence of a warm, humid maritime tropical air mass with dew points in the mid-70s that sharply limits radiational cooling. High relative humidity, light winds, and potential overnight cloud cover from scattered showers further suppress temperature drops, while the urban heat island and proximity to the Gulf Stream maintain elevated baselines typical of early summer. The near-even split between 80–81°F and 82–83°F outcomes stems from minor uncertainties in model timing of any clearing versus lingering moisture, which can shift the minimum by 1–2°F. Historical June averages (lows near 77–78°F) underscore how current conditions trend warmer, keeping trader focus on these narrow bins.