Last updated: August 27, 2025
In December, the average temperature in Grantham, United Kingdom hovers around 6°C (42°F). While you might experience a chilly minimum of -3°C (26°F), the mercury can rise to a pleasant 15°C (59°F). Expect 74 mm (2.9 in) of precipitation over approximately 15 days, with a high average humidity of 90%—perfect for those who appreciate a cozy, misty atmosphere!
In December in Grantham, the average temperature is 6°C (42°F), with maximums reaching 15°C (59°F) and minimums dropping to as low as -3°C (26°F). Be prepared for a chilly climate and pack accordingly to ensure a comfortable travel experience.
In Grantham in December, the precipitation amount is 74 mm (2.9 in) over the course of 15 days.
In Grantham in December, humidity is 90%. With an average temperature of 6°C (42°F), this humidity feels like a heavy blanket wrapping around you, making every step feel more laborious and causing your clothes to cling uncomfortably, which can be quite challenging for traveling.
In Grantham in December, the maximum UV index is 1, which corresponds to a low Exposure Category. This means you have a time to burn of 45 minutes. For more details, you can check the Hourly UV Index in Grantham.
UV Risk Categories
Weather in Grantham varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Grantham, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 5°C (41°F) | 46 mm (1.8 inches) | 90% | low |
| February Weather | 6°C (43°F) | 57 mm (2.3 inches) | 88% | low |
| March Weather | 7°C (45°F) | 61 mm (2.4 inches) | 86% | moderate |
| April Weather | 9°C (48°F) | 35 mm (1.4 inches) | 84% | moderate |
| May Weather | 12°C (54°F) | 64 mm (2.5 inches) | 80% | high |
| June Weather | 16°C (60°F) | 78 mm (3.1 inches) | 81% | very high |
| July Weather | 18°C (64°F) | 72 mm (2.8 inches) | 76% | very high |
| August Weather | 17°C (63°F) | 75 mm (3.0 inches) | 77% | high |
| September Weather | 15°C (59°F) | 57 mm (2.3 inches) | 85% | moderate |
| October Weather | 11°C (53°F) | 76 mm (3.0 inches) | 90% | moderate |
| November Weather | 8°C (46°F) | 58 mm (2.3 inches) | 92% | low |
| December Weather | 6°C (42°F) | 74 mm (2.9 inches) | 90% | low |