WEATHER FORECAST

The weather in Loudon during late September is noticeably cooler and more changeable compared to the summer races. Fans can expect true early autumn conditions in New Hampshire, with crisp mornings and mild afternoons.

Average temperatures

• Daytime Highs: Typically in the upper 60s to mid-70s °F (20–24 °C).
• Nighttime Lows: Often in the upper 40s to mid-50s °F (9–13 °C).

Weather conditions

• Daytime: Comfortable temperatures with a mix of sunshine and passing clouds. Unlike August, humidity is much lower, making for pleasant viewing conditions. Occasional light showers are possible, but prolonged rain is less frequent.
• Evening: Cooler air sets in quickly after sunset. A light jacket or hoodie is recommended for the grandstands or camping areas.

Rain possibility

September averages around 3.5 inches (90 mm) of rainfall in Loudon. While the risk of late-afternoon showers or a passing front exists, long rain delays are less common than in midsummer. Always check the forecast closer to race week.

Wind

Winds are generally light to moderate (5–12 mph / 8–19 km/h). Gusts can increase with passing weather fronts, but overall wind is not usually disruptive.

Sun protection

The UV index is moderate this time of year, but sunscreen and sunglasses are still advisable, especially on clear days. With the cooler air, it’s easy to underestimate sun exposure.

For the most accurate information, it is advisable to check a reliable weather forecast closer to the date of your visit, as weather conditions can change from year to year. For example, we recommend the Windy app.