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Grantham — Current Water Temperature, Annual Trends and Forecast

This page provides information on the current water temperature in Grantham, trends, monthly ranges and the forecast for the coming days.

Grantham, United Kingdom
Grantham, United Kingdom © Tim Heaton, CC BY-SA 2.0

Current Water Temperature

14.7°C
Today
14.7°C
Yesterday
16.1°C
A Week Ago
Get instant access to real-time water temperatures for this and all other locations with our iOS and Android apps.

Water Temperature in Grantham today is 14.7°C.

Water Temperature: Daily Trends, Historical Records, and Forecast

⚠️ As of today, the minimum water temperature ranges from 54°F (12°C) to 60°F (15°C). The water is significantly warmer, and swimming becomes possible for most people. However, caution may still be required for prolonged stays in the water, as extended exposure can cause discomfort. This is a suitable temperature range for short swims and for those accustomed to cooler water. For more comfortable swimming, it is recommended to use proper gear. It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.

Water Temperature Chart Over the Last 30 Days

From May 10 to June 10

Table of Daily Sea Temperature Data

Date Current Average Forecast
JUN 315.2°C18.0°C
JUN 415.2°C18.0°C
JUN 515.2°C18.0°C
JUN 615.2°C18.0°C
JUN 714.7°C18.0°C
JUN 814.7°C18.0°C
JUN 1014.7°C18.0°C
JUN 1118.0°C14.9°C
JUN 1218.0°C15.0°C
JUN 1318.0°C15.2°C
JUN 1418.0°C15.4°C
JUN 1518.0°C15.5°C
JUN 1618.0°C15.7°C
JUN 1718.0°C15.9°C

* Current - Actual water temperature value

** Average - Average water temperature on this day in recent years

*** Forecast - Our water temperature forecast

Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.

Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.

Monthly Water Temperature Range (Min, Max & Average)

Month Min Avg Max
January0°C3°C6°C
February0°C4°C7°C
March2°C6°C9°C
April6°C9°C12°C
May9°C14°C19°C
June13°C18°C22°C
July14°C18°C23°C
August14°C18°C23°C
September10°C15°C19°C
October8°C11°C14°C
November3°C7°C11°C
December0°C4°C8°C

Grantham: Weather Forecast

June 9

° / °
light drizzle
rain: 96% | wind:

June 10

° / °
light drizzle
rain: 63% | wind:

June 11

° / °
slight rain
rain: 67% | wind:

June 12

° / °
overcast
rain: 22% | wind:

June 13

° / °
mainly clear
rain: 10% | wind:

Location & Local Information

Grantham, a market town in Lincolnshire, lies near the upper reaches of the River Witham, where the river begins its slow journey toward Lincoln and the Fens. In this part of its course, the Witham is narrow and fresh, reflecting the mild but changeable climate of eastern England. During winter, the water temperature typically ranges between 3 and 5°C (37–41°F), remaining cold and brisk. By spring, it gradually warms to around 8–10°C (46–50°F). In midsummer, during July and August, the river can reach 17–19°C (63–66°F), particularly in shallow and sheltered areas. As autumn returns, it cools again to about 11–13°C (52–55°F), keeping a steady, refreshing flow through much of the year.

Swimming in the River Witham near Grantham is possible but not common, as the upper sections are shallow and often bordered by farmland. Those who do swim usually choose calm summer days and quiet stretches away from vegetation or livestock. The water is generally clean, though its flow can quicken after rainfall. Many people prefer to enjoy the river from the banks through walking, picnicking, or kayaking. The surrounding countryside, with its rolling fields and nearby Belton House estate, offers peaceful scenery that complements the gentle rhythm of the Witham Valley.

Nearby Locations

Frequently Asked Questions

What is the current water temperature in Grantham?
Water Temperature in Grantham today is 14.7°C.
What is the water temperature in Grantham during the summer months?
The water temperature in Grantham in summer fluctuates in the range of 13°C - 23°C.
Is it possible to swim in Grantham (United Kingdom) in River Witham and what are the possibilities for this?
It is possible to swim in the River Witham through Grantham, but there are no official lifeguarded bathing sites, so people either swim informally at their own risk—mindful of changing water quality, currents and boat traffic—or join organised open‑water swim groups or use the town’s supervised indoor pools for a safer option.