Last updated: June 24, 2025
In May, the average temperature in Grand Coulee, United States hovers around 15°C (59°F). Expect a minimum of 1°C (34°F) and a maximum of 31°C (89°F), offering a wide range of conditions. During this month, precipitation totals around 37 mm (1.4 in), typically spread over 7 days. Additionally, the average humidity reaches a comfortable 77%, making for an intriguing climate experience!
In May in Grand Coulee the average temperature is 15°C (59°F). Maximum can reach 31°C (89°F) and minimum can be as low as 1°C (34°F). Be prepared for a wide range of temperatures during your trip, from warm days to potentially cool nights.
In Grand Coulee in May, the precipitation amount is measured at 37 mm (1.4 in) over a span of 7 days.
In Grand Coulee in May, humidity is 77%. With an average temperature of 15°C (59°F), this humidity feels like a warm blanket enveloping you, making it essential to stay hydrated and choose light, breathable clothing for comfortable travel.
In Grand Coulee in May, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Grand Coulee.
UV Risk Categories
Weather in Grand Coulee varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Grand Coulee, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -2°C (28°F) | 67 mm (2.6 inches) | 85% | low |
| February Weather | -2°C (28°F) | 47 mm (1.9 inches) | 86% | moderate |
| March Weather | 4°C (39°F) | 46 mm (1.8 inches) | 86% | moderate |
| April Weather | 9°C (48°F) | 39 mm (1.6 inches) | 82% | high |
| May Weather | 15°C (59°F) | 37 mm (1.4 inches) | 77% | very high |
| June Weather | 20°C (68°F) | 13 mm (0.5 inches) | 79% | very high |
| July Weather | 24°C (75°F) | 4 mm (0.1 inches) | 77% | very high |
| August Weather | 23°C (74°F) | 8 mm (0.3 inches) | 62% | very high |
| September Weather | 17°C (62°F) | 24 mm (1.0 inches) | 60% | high |
| October Weather | 8°C (48°F) | 42 mm (1.7 inches) | 80% | moderate |
| November Weather | 3°C (37°F) | 51 mm (2.0 inches) | 87% | moderate |
| December Weather | -2°C (29°F) | 57 mm (2.2 inches) | 86% | low |