Winter in coastal areas is milder than that in inland areas of the same latitude, so spring in Dalian must come earlier than in Beijing, right? Why?

It is not appropriate to answer this question with right or wrong.

When you say "spring is coming", do you mean that the temperature has reached a certain level? Or did the flowers sprout? At present, it is generally said that "spring is coming" when the highest temperature reaches a certain level during the day 10, but in fact, the change of solar terms is very complicated. Even if the temperature is reached and some factors are not available, flowers and plants will not germinate. The change of solar terms will be different in cities with the same latitude and different longitudes. This will be more profound for beekeepers. It is based on this difference that they compete to bloom, usually from west to east.

As for the temperature, even if the temperature is the same, there are great differences between coastal cities and inland cities. Generally speaking, at the same temperature, coastal cities feel colder, because the air humidity is high, which leads to more heat dissipation from the skin. In cities with the same latitude, the temperature in coastal cities is generally higher than that in inland cities, because the heat capacity of seawater is large, and the ocean will transfer heat to the land in winter.