Start with exposure, not just the temperature
A number on a forecast is useful context, but it does not describe the full outing. Before leaving, look at the expected temperature range, wind, precipitation, heat or cold alerts, and the part of the day your child will actually be outside.
Then make the plan specific: stroller versus walking, shade versus open playground, a short handoff versus a long outing, and whether wet clothes or a change of layers would be hard to manage away from home.
Keep a simple change plan
Use one clear decision point rather than trying to predict every possibility. A dry layer, a water-resistant outer layer, a shaded break, or an earlier return can be more useful than adding extra bulk before you leave.
When conditions are extreme, local alerts and venue guidance take priority. The app can help organize clothing context, but it cannot decide whether an outing is appropriate for your child.
Use official weather guidance when conditions become a safety question
National Weather Service and CDC guidance can help parents recognize when heat, cold, or a winter storm needs a different plan. For a child with a health condition or a concerning symptom, use a qualified clinician rather than a general planning guide.