Are only older chemistries affected by temperature? If temperature impacts plant growth, all herbicides will be impacted.
By "Quats", do you mena PSI inhibitors? Paraquat and diquat are known to react in a matter of hours, even in complete darkness. Sure, they work minutes quicker in direct sunlight, but can you qualify it as "slow" if it takes 60 minutes vs 45 minutes?
Cloudy weather will impact triazines, but just the cloudy weather alone usually isn't the culprit. It is a combination of temperature, moisture, and sunlight. Triazines are very soluble in water and steady drizzles over time ofter reduce root uptake.
In short, its just gonne take a little bit longer than you're used to. That's all.