Abstract: The 1970-1985 daily-averaged pressure dataset of Shanghai is used to calculate its associated dimension D and the second-order Reiyi entropy, K₂, as the approximation of Kolmogorov's entropy, in terms of the phase space continuation, indicating the fractional dimension D = 7.7-7.9 and positive K₂≈0.1.This shows that the attractor for the short-term weather evolution in the monsoon region of China exhibits a choatic motion.The direct estimate of K₂ yields a roughly 10-day scale of the lead time T= (1/K₂) ,a result which is in agreement with that obtained earlier by the dynamic-statistical approach.Examined during the continuation of phase space is the effect of the lag time τ.Calculations show that D and K₂ are convergent with respect to τ.The daily averaged pressure series employed are treated by the continuation of phase space with τ=5, with the coordinate components independent of each other, and the dynamically characteristic quantity of the system is found stable and thus reliable.