The manufacturer of Russian smart bombs (KCRV) admitted, in a late 2018 media interview, that Russia found that its laser-guided missiles and fire control systems for dumb bombs were not prepared for the desert dust and heat conditions encountered in Syria. The problems were fixed but not before a lot of pilots (and Russian air controllers on the ground) complained that accuracy was often way off. Further investigation found that Russian laser designators were not equipped to handle the misleading heat and light conditions sometimes encounters on the ground. The latest fire control systems for unguided bombs, which worked quite well under most conditions, especially in European conditions, were often way off in Syria. KCRV urged the air force to use more GPS guided bombs in the meantime but the air force could not afford it. So accuracy suffered until the fire control systems and laser designators were modified. Making these admissions was a wise move because now that Russian missile and smart bombs are “combat tested” Russia enhances its reputation by demonstrating that their weapon designs are not perfect and they are willing to fix problems quickly and effectively.
Even American equipment, which has long experience with these problems, still encounters climate conditions that were not anticipated. For example in 2009 F-22 fighters, stationed in Guam, developed electrical problems because of the very wet (100 inches, or 2.5 meters of rain a year) conditions in that part of the world. The high humidity meant that air intakes on the fighter, which help cool off electronic components, let in so much moisture that some electronics got wet and shorted out. Adjustments had to be made and were.
Such problems are common when a new aircraft operates in a new environment. This experience goes back to World War II. A more recent example was when joint exercises were first held in Egypt during the 1980s. There, U.S. aircraft and armored vehicles got their first workout in the Egyptian desert. Turned out the sand there was different than what was found in American deserts, and the standard air filters were more quickly overwhelmed. A similar problem occurred when large U.S. air and ground forces went to Saudi Arabia in 1990.
The sand problem and its impact on engines were known from World War II, and the engineers thought they had it taken care of it in the decades after 1945. But it just goes to show you that you can't test enough for these things. This, despite the fact that new aircraft and ground vehicles go through extensive testing in deserts, rain forests and very cold environments. Moreover, you might not see problems develop until many vehicles have operated in new conditions for weeks or months.
These problems can be fixed rather quickly, although often with higher costs and more work on the part of the crews and maintenance personnel. In the case of the F-22 problem, temporary fixes were made, and some components are being redesigned so that they handle the high humidity better.