O'Fallon Weather in May

May in O'Fallon averages 25°C (77°F) during the day and 14°C (57°F) at night. Quite a bit of rainfall is typical this month, with around 129 mm (5.1 in) on average. An umbrella is a good idea.

Rainfall in O'Fallon in May

You can expect rain on roughly 14 days based on historical data, averaging 129 mm (5.1 in) for the month. The rain this month tends to fall in heavier spells rather than light drizzle. When it rains, showers can be significant.

Temperature in O'Fallon in May

In May, O'Fallon sees high temperatures, with highs of 25°C (77°F). Nights drop to around 14°C (57°F). This kind of day-to-night contrast is typical for this time of year. Nights cool down to 14°C (57°F), so a light jacket or extra layer is useful once the sun goes down. On the plus side, the cooler nights make for comfortable sleeping conditions.

Sunshine in O'Fallon in May

The days are predominantly sunny, with an estimated total of around 269 hours of sunshine. These sun-filled days are perfect for playing sports, visiting parks, or going for a bike ride.

Should you favor a climate that's both dry and comfortably warm, October typically offers the most agreeable circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.