4-5 May WRE FinTrailO, Porvoo/Tampere, Finland. TempO + 2 x PreO.  Information here
22-23 June ECTO Panamacor, Portugal (pre-WTOC). TempO + PreO. Information here
23-29 June   World TrailO Championships, Idanha-a-Nova, Portugal. Website and Bulletin 2 here
28-30 June   Kapa, Latvia, 3-day FootO and 2 x PreO + TempO. Information here 
15-18 July WRE FIN5 2019, incl. 3 x PreO + 2 x TempO competitions. Can do both FootO & TrailO. Info here
26 August   British TrailO Championships, Scarborough (linked with White Rose w/e). Info here
14-15 September ECTO+WRE Polish TrailO Championships. TempO + PreO
5-6 October ECTO+WRE Nordic Match, Landvetter, close to Gøteborg airport, Sweden. Night PreO + 2 x PreO
12-13 October WRE Bukowa Cup, Poland. PreO + TempO
Nov-Dec   First Asian TrailO Championships, Hong Kong (PreO + TempO + Relay)
early November   World TrailO Championships, Hong Kong
    World TrailO Championships, Poland

WRE = IOF World Ranking Event

ECTO = European Cup in TrailO

The following events usually have one or more TrailO competitions along with FootO competitions:

Portugal O-meet, February (PreO)

Lipica Open, Slovenia (PreO)

JK, Easter weekend (TempO + PreO)

British Orienteering Championships and British TrailO Championships (PreO) on the same weekend, same venue

Wawel Cup, Poland, July (PreO)

Swedish O-Ringen, July (5 x PreO)

Scottish 6-Days, July-August (PreO)

Hungaria Cup, August (4 x PreO)

Cerkno Cup, Slovenia, August (PreO)

White Rose Weekend, August (PreO)