That said, a small population of moss will be found in almost all lawns at most times of the year. The degree of population will depend on many factors, eradicating it entirely is not realistic. The aim of a complete lawn treatment programme is to keep it under control, and not let it dominate the lawn or thin out the grass plant population. A little bit of Moss is normal and should not be a cause for alarm.
The growth cycle of Moss
During the summer months, the moss population of your lawn will be inactive. The weather and its natural growth cycle will have dried it out, and it will have shrunk back. It will not be releasing active fresh spores or trying to increase its colonisation of the lawn. The extent to which it is dormant may vary, heavily shaded areas where moisture is retained will see the Moss population hold onto its active state longer than areas exposed to more light. Shelter from the drying properties of wind has the same effect.
When moisture levels rise, and temperatures drop in Autumn, the Moss will again become active. Its growth cycle will resume and so will its production of fresh spores. This is one of the compelling reasons for getting lawn scarification done in late summer: there is no risk of spreading live Moss spores during the scarification process. Depending on temperature, the Moss in your lawn will continue to try and grow throughout the winter and into early spring.