Mars and Venus
You won't be too surprised to know that temperature records for both planet are patchy.
For Venus, well we really have a very primitive understanding of the Venusian atmosphere and how it circulates heat. It is about 100 times the mass of the Earth, so we do know it holds a huge amount of heat and changes very slowly. A Japanese probe which would have performed long term measurements of the atmosphere failed to enter Venusian orbit in 2010. At the moment there are no probes planned to do that task.
We have better records for Mars going back to Viking in the mid 1970s. On a planet wide scale the atmosphere has cooled noticeably since Viking which arrived at the end of a long period of planet-scaled dust storms. The storms served to warm the atmosphere and probably pushed temperature above trend.
There was a large retreat of the Southern Polar ice cap on Mars from 2001 to (IIRC) 2005, but this was not seen elsewhere on the planet. It is thought this was a regional effect caused by dark dust being carried from equatorial regions towards the pole. The dust absorbed heat and melted the ice. But even this is uncertain as the Southern Cap is very thin, some years it disappears entirely, others it persists.