The research aims to study the effect of Seasonal variations in yields and qualities of agar seaweed Pterocladia capillacea. The results show that there is a clear impact of the Seasonal variations in the yield, physical and chemical properties of the extract agar. Agar yields ranging from 10.1 to 33.8% and has been the highest in the month of June and below 33.8% in December, 10.1% of the years 2014 to 2015. Reached the maximum value of the strength of the gel in June, 789 g/cm2 and the minimum value of 183 g/cm2 through December and the average rate of sulfates 3.42%. The viscosity values ranged between 35.7 and 81.4 cP, and recorded the highest value in July 81.4 cP. Melting temperature ranged 78- 86.5 °C and Gelling temperature from 35 to 25 °C.