Last updated: June 24, 2025
In Waterloo, United States, the average temperature in May is a comfortable 17°C (63°F). However, temperatures can vary significantly, with lows dipping to 2°C (36°F) and soaring up to a scorching 37°C (99°F). Expect a fair amount of rainfall too, with an average precipitation of 146 mm (5.8 in) spread over about 15 days. The air tends to be quite humid, with an average humidity of 78%, making for a lush environment.
In May in Waterloo, the average temperature is 17°C (63°F), with maximums reaching up to 37°C (99°F) and minimums dropping as low as 2°C (36°F). It's essential to pack versatile clothing to comfortably enjoy both warm and cooler moments during your travels.
In Waterloo in May, the precipitation amount is 146 mm (5.8 in) spread over 15 days, indicating a relatively wet period during that time.
In Waterloo in May, humidity is 78%. With an average temperature of 17°C (63°F), this humidity feels like a warm, enveloping blanket, making traveling slightly uncomfortable as you navigate the sticky air, prompting the need for frequent breaks in cooler, shaded areas.
In Waterloo in May, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Waterloo.
UV Risk Categories
Weather in Waterloo varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Waterloo, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -4°C (25°F) | 32 mm (1.3 inches) | 76% | moderate |
| February Weather | -4°C (26°F) | 30 mm (1.2 inches) | 80% | moderate |
| March Weather | 5°C (41°F) | 97 mm (3.8 inches) | 73% | high |
| April Weather | 10°C (51°F) | 54 mm (2.1 inches) | 74% | very high |
| May Weather | 17°C (63°F) | 146 mm (5.8 inches) | 78% | very high |
| June Weather | 24°C (76°F) | 126 mm (5.0 inches) | 82% | very high |
| July Weather | 26°C (78°F) | 74 mm (2.9 inches) | 83% | very high |
| August Weather | 24°C (75°F) | 100 mm (4.0 inches) | 80% | very high |
| September Weather | 21°C (70°F) | 83 mm (3.3 inches) | 75% | very high |
| October Weather | 11°C (53°F) | 115 mm (4.5 inches) | 75% | high |
| November Weather | 5°C (40°F) | 31 mm (1.2 inches) | 82% | moderate |
| December Weather | 0°C (32°F) | 40 mm (1.6 inches) | 83% | low |