Will weather affect Endurant? Minimally. Once colorants are dried and cured, weather has minimal affects on Endurant turf colorants. You may apply Endurant turf colorants when frost, dew or a very small amount of moisture is on the grass blades. This may actually increase uniformity of color application. But it is not necessary. If a heavy rain were to come prior to Endurant drying, that could cause the paint to wash off. Generally, just allow grass to dry for 8 hours before a rain and up to 24 hours before a heavy rain. Endurant is dry to the touch in most cases within an hour.
Avoid windy conditions during application. High winds could cause accidental overspray and spray drift.
High humidity may require longer dry times.
Geoponics gave Endurant its name for the colorants' durability in all weather. Just be sure Endurant has dried and cured. A related question to "will weather affect Endurant?" is "How long does Endurant last?" Check out the answer here.