If you like walking and can handle the heat then Merida is an excellent city to get to know by walking perhaps with help from the occasional bus or taxi. The city within the limits of the periferico is fairly compact and most areas can be accessed by walking or a short bus ride and walking. Of course the famous Merida heat is always a factor in any outdoor activities and walking any distance is best avoided between 11-4pm. The ideal time for walking is early morning when the air is coolest. If you venture out shortly after sunrise (around 6.30am) you will encounter many locals going for early morning walks or jogs. By 9am the weather really starts to heat up and by 11am it’s pretty intense. After 11am it’s usually best to be indoors if possible. By 4pm usually the worst of the heat is over and the sun goes down around 6pm. This is also a good time to walk with no worries about finding shade. Also, it is best to avoid walking along major traffic arteries as the noise and pollution from traffic is beyond annoying and negates any benefits or pleasures of walking. It goes without saying that good footwear is essential if you plan on going. Good sturdy walking shoes or boots (Decathlon has a good selection) are recommended. Also a wide brimmed hat or parasol is a great help if the sun is shining.

Mérida is generally a very safe city by Mexican and international standards even at night. The biggest risk for pedestrians  is from the traffic and the poor state of repair of many sidewalks. Crossing roads should be done with utmost care and the assumption that the drivers are blind or crazy – which some of them may be. The quality of the sidewalks varies tremendously from the downtown core where most (but not all) are well maintained to some suburbs where sidewalks are an afterthought. Sidewalks are more often than not highly irregular with abrupt changes in width, height and inclination. Sometimes sidewalks will just arbitrarily stop leaving you with no option but to walk on the roadway. Apparently it is the responsibility of the home owner to maintain the sidewalk outside their residence since the structure and surface are usually aligned with the house style.  Regardless of the structure and size of the sidewalk there are often many obstacles to be aware of and overcome. First, the debris. There are all sorts of debris scattered on sidewalks from large palm tree branches  and rocks to general garbage and animal excrement. Potholes are not exclusive to roadways and sidewalks have their fair share so be careful or you may risk an ankle or worse.
Overall Mérida is great city to get to know by walking so go ahead and explore.