To check Environmental Conditions for Mould Growth, Thermometer and Humidity Monitors start from $20 on Amazon - which is good value to help check monitor mould conditions.
Air Humidity: Between 70% and 90% is the optimal humidity level for mould growth. Mould is a type of fungus that grows by consuming organic materials, such as wood, paper, and fabrics. It thrives in damp, warm, and poorly ventilated environments, and high levels of humidity provide the moisture that mould needs to grow and reproduce.
Air Temperature: The optimal temperature is between 21 and 32 degrees Celsius (70 and 90 degrees Fahrenheit) for mould growth. As mould thrives in damp, warm, and poorly ventilated environments, and warm temperatures provide the warmth that mould needs to grow and reproduce.
If the humidity is high and temperature warm for around a week, these conditions ae ideal for mould growth.