Last updated: June 24, 2025
In May, the average temperature in Harriston, United States hovers around 18°C (65°F), offering a comfortable climate. However, be prepared for a range of temperatures, with lows of -1°C (31°F) and highs reaching 32°C (90°F). Expect about 110 mm (4.3 in) of precipitation spread over 13 days, contributing to an average humidity of 78%. Whether you're exploring or relaxing, this month presents a mix of weather conditions to consider!
In May in Harriston, the average temperature is 18°C (65°F). Maximums can reach 32°C (90°F), and minimums can be as low as -1°C (31°F). It's a great time to visit, as you can experience a wide range of weather conditions, making it ideal for both outdoor activities and cozy indoor exploration.
In Harriston in May, the total precipitation amount is 110 mm (4.3 in) over the course of 13 days.
In Harriston in May, humidity is 78%. With an average temperature of 18°C (65°F), this humidity feels like a warm, enveloping blanket, making travel quite muggy and potentially uncomfortable, as it can leave you feeling sticky and fatigued more quickly than usual.
In Harriston in May, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Harriston.
UV Risk Categories
Weather in Harriston varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Harriston, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 2°C (35°F) | 60 mm (2.4 inches) | 86% | moderate |
| February Weather | 5°C (40°F) | 87 mm (3.4 inches) | 86% | moderate |
| March Weather | 7°C (46°F) | 67 mm (2.6 inches) | 86% | high |
| April Weather | 13°C (55°F) | 108 mm (4.2 inches) | 84% | very high |
| May Weather | 18°C (65°F) | 110 mm (4.3 inches) | 78% | extreme |
| June Weather | 22°C (72°F) | 89 mm (3.5 inches) | 79% | very high |
| July Weather | 25°C (77°F) | 59 mm (2.3 inches) | 70% | very high |
| August Weather | 24°C (75°F) | 108 mm (4.2 inches) | 59% | very high |
| September Weather | 21°C (69°F) | 102 mm (4.0 inches) | 68% | very high |
| October Weather | 15°C (60°F) | 106 mm (4.2 inches) | 80% | high |
| November Weather | 7°C (44°F) | 76 mm (3.0 inches) | 86% | moderate |
| December Weather | 4°C (39°F) | 84 mm (3.3 inches) | 85% | moderate |