Mexico City in March turns purple, and yes, it is as lovely as the photographs. The jacarandas along the big avenues and in the leafier neighbourhoods come into flower, usually peaking some time in the month, and with dry weather and more than eleven hours of sunshine a day it is one of the easiest months for a first visit.
Start on Paseo de la Reforma, the grand boulevard with jacarandas down both sides, and do it on a Sunday morning if you can. Every Sunday except the last of the month, the city closes Reforma to cars until early afternoon for Muévete en Bici, so you can walk down the middle of the road or borrow a bike and ride it. Afterwards, wander south into Condesa, where Parque México and Parque España sit under more jacarandas, or head out to Coyoacán for colonial streets and a slower pace.
Will the altitude get to you? Probably not much. The city sits at about 2,240 metres, and most visitors feel nothing worse than a mild headache, or a shortness of breath on the stairs, for a day or two. Take the first day gently and drink plenty of water, bottled or purified, since the tap water isn't for drinking. Go easy on the mezcal too, because alcohol hits harder up here.
The sun is what catches people out. At this height it burns even when the air feels cool, so wear sunscreen and a hat on those long jacaranda walks. Afternoons reach about 27°C, yet nights drop to around 10°C, and a terrace table that feels perfect at six is chilly by ten. Carry a jumper.
Air quality can dip in the dry season, when ozone builds on still, sunny days. If you have asthma or another breathing condition, check the live readings each morning and save the longest walks for the cleaner days.
Teotihuacan, the ancient city of pyramids north-east of the capital, makes an easy day trip, but not on the spring equinox, around 20 or 21 March, when thousands of people dressed in white arrive to greet the sun. Go on a weekday earlier or later in the month, and set off early. There is almost no shade along the Avenue of the Dead, and by midday the sun on all that bare stone is fierce.