There are several events taking place in Brussels on a particular date every year that are well worth visiting – such as the flower carpet, museum night fever and others. They are a great option for a different type of a Sunday or a great night out with or without children. (I have purposefully left out November because I do not remember any Brussels events organised during that month.)
January
- Plaisirs d’hiver – There is still a Christmas market to visit that lasts until 7th January. Numerous little houses offering food and presents can be found in the city centre around Grand Place and Place St Catherine. Also interesting to keep an eye on are pop up Christmas markets around the city such as Place Sablon and Place Ambiorix. http://www.plaisirsdhiver.be/en/
- Brussels Jazz Festival Flagey – The festival lasts 10 days on several locations in the city and you can hear some really good jazz for a very ok price. https://www.flagey.be/en/group/5105-brussels-jazz-festival-2019
February
- Bright Brussels – It is a lovely light festival taking place around the city to light up dreary February nights. Every year new authors present their creations in buildings around Brussels you would maybe not normally visit. https://visit.brussels/en/sites/bright
- Museum Night Fever – My absolutely favourite event of the year and if you are a museum fan, I would absolutely recommend it. Many museums around the city are open late in the evening with special guiding tours, bars, live music present on locations to provide for a great night out. There are activities for children and adults alike and it starts at 19:00 and lasts until early hours of the morning if you still have the energy 🙂 http://www.museumnightfever.be/
March

- BANAD festival – The Brussels Art Nouveau and Art Deco Festival promotes the Art Nouveau and Art Deco heritage in Brussels. The best part is that you get to see art deco heritage that is normally not open to the public and are only open for those events. https://www.banad.brussels/en
April
- Royal Greenhouses of Laeken – These botanical gardens in the possession of the royal family of Belgium are available for a visit for 3 weeks in the year between April and May. It provides for a beautiful walk among architecture of Victor Horta and many different flower species all in bloom. https://www.monarchie.be/fr/agenda/ouverture-des-serres-royales-de-laeken-2019
- Brussels Short Film Festival – Festival of short movies taking place in different cinemas around Brussels http://bsff.be/en/who-we-are/
- Floralia -It is a spring flower exhibition in the park and the greenhouses of the castle of Grand Bigard (Groot-Bijgaarden) with the park of 14 hectares incorporating nearly all spring bulb varieties. For the new flowering time, the gardeners of the castle have planted by hand more than one million bulbs. Special attention goes to the tulips, with almost 400 varieties, hyacinths and daffodils are also well represented. http://www.kasteelgrootbijgaarden.be/en/floralia-brussels/

- Balkan Trafik – This festival celebrates the culture of the South East Europe, Balkan area through concerts, theatre, literature, cinema and other art forms over 5 days in Brussels. It is a lot of fun and truly a great experience. https://balkantrafik.com/
May
- Fete d’Iris – The translation is an Iris party and Iris is the symbol flower of the Region of Brussels. There are many activities, live events, performances across the city and the best part of the story is that it is all for free. https://fetedeliris.brussels/
- EU Open Day – I know this may be something most of you are aware of but it is really fun to get to know the institutions and spend a day roaming around the EU neighbourhood. And you get a lot of freebies while you are at it 🙂 https://europa.eu/european-union/about-eu/symbols/europe-day_en
- Vaux-hall summers – every weekend between May and September, in the Vaux-hall of park Cinquantenaire there is a rich cultural programme organised by the city of Brussels. https://vauxhallsummer.bruxelles.be/
June
- Couleur caffe – one of the better known Brussels music festivals right under the well-known Atomium building that runs for 3 days a row. https://www.couleurcafe.be/en/
- Fete de la musique – another music festival but this one is for free and takes place for 3 days https://www.fetedelamusique.be/
- Ommegang – Those in power at the time in Brussels decided to show off the wealth and glory of their city by organising an Ommegang (which means walking round or procession) where for this one special occasion municipal bodies, guilds and patrician Brussels as well as the nobility from surrounding regions and the high clergy passed in solemn procession with the pomp and circumstance that clearly announced their status and privileges, while at the same time honouring the greatness of the emperor. http://www.ommegang.be/?lang=en
July
- Bruxelles les Bains – http://www.bruxelleslesbains.be/
August
- Brussels Flower carpet – This is probably the most well known Brussels event and it happens every second year and not every year where the Grand Place is decorated with an amazingly colourful flowers that are shaped like a carpet and every year they dedicate it to another country/region of the world. http://www.flowercarpet.brussels/en
- Brussels Summer Festival – This is another urban music festival, goes on for 10 days and has been organised since 2002 in the city. http://bsf.be/
September
- Belgian Beer Weekend – It lasts for 3 days and the best part is that it is organised by the Knighthood of the Brewer’s Paddle and Belgian Brewers. A Knighthood guys! Small and big breweries present their beer at the Grand-Place. The entrance is free, the tastings have to be paid. http://www.belgianbrewers.be/en/
October
- Nuit Blanche – white night showcases the public space and dozens of sites in the capital by means of contemporary artistic creation. Cultural venues, shop windows, school playgrounds, car parks, churches, stations, fountains, streets and squares are all potential locations. It is another great night out to walk around different venues in the city. http://nuitblanche.brussels/en/edition-2019/
- Brussels Electronic Marathon – The Brussels Electronic Marathon is 3 days of electronic music from the local scene with parties, live concerts, DJ sets, workshops & films. https://www.bem.brussels/
December
- Floridylle – This botanical garden in the little town of Meise a bit outside ofBrussels organises a lovely night walk with lights and music performance of the plants across a huge park. At the end there is also a place to have a drink and food around fire and altogether it is a really lovely place to be in case you are in Brussels between Christmas and New Years. The official page does not work at the moment but this may be of help but it is in Flemish:https://www.meise.be/activiteitendetail/984/winterfloridylle-in-de-plantentuin-meise

who has more beautiful photos of how it actually looks.