There could be several potential explanations for the "thud" sound you heard on your roof. Here are a few possibilities:
Animal activity: It's possible that the sound is caused by animals such as birds or squirrels landing or jumping on your roof. These creatures may be searching for food, nesting, or simply moving around. Keep in mind that some animals can be quite noisy when they interact with structures.
Falling objects: If there are trees near your house, it's possible that branches or other debris could be falling onto your roof, creating the thudding sound. This could occur due to wind, storms, or even animals moving in the trees.
Expansion and contraction: Changes in temperature can cause materials on your roof, such as metal or wood, to expand or contract, resulting in a thud-like noise. This is more common in extreme weather conditions when there are rapid temperature fluctuations.
Weather-related factors: Adverse weather conditions like hail or heavy rain can create a thudding sound when they hit your roof. While these sounds are usually temporary, they can be noticeable and concerning.
Roof settling: Roofs can make noise as they settle and adjust over time. This is particularly common in newer houses or after significant changes in temperature, such as during the transition from hot to cool weather.
If you're concerned about the source of the sound, it may be helpful to inspect your roof from a safe vantage point or consider reaching out to a professional to assess the situation.