Harrow Temperature by Month

Harrow, Greater London, United Kingdom has an average annual maximum temperature of 15°C (59°F), ranging from 9°C (48°F) in January to 23°C (73°F) in July. Below you'll find a full monthly breakdown and a comparison with cities worldwide.

Visitors to Harrow will encounter a climate influenced by big temperature differences across the year. Nighttime temperatures range from 14°C (57°F) in July to 3°C (37°F) in January.

The chart below illustrates the average maximum day and minimum night temperatures in Harrow by month:

From around 4 AM to 6 AM temperatures are at their lowest; by 3 PM they've climbed to their daily peak. July, the warmest month, averages 219 hours of sunshine.

The chart below shows the average temperature throughout the year:

Harrow's average annual maximum temperature is 15°C (59°F). To put that in context, here's how it compares to a few well-known destinations:

Athens, Greece sits at 23°C (73°F) on average, with hot dry summers and mild winters characteristic of the Mediterranean.

Glasgow, Scotland averages 13°C (55°F) a year, mild but often grey, with cold winters and rarely hot summers.

New York City, USA averages 17°C (63°F) a year, with hot humid summers and cold winters that bring regular snowfall.

Adelaide, Australia averages 21°C (70°F) a year, with warm summers, mild winters, and relatively low rainfall year-round.

Temperature alone doesn't tell the whole story, humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.

In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.

In Harrow, January is the coolest month, with average highs of 9°C (48°F) and humidity around 80%, considered very high. For a full picture, see our humidity page.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Seasonal temperature shifts influence more than just how warm it feels, they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.

Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in Harrow this rarely lasts long on the ground.

For more on Harrow's weather, including monthly rainfall, sunshine hours, and humidity, visit our Harrow climate page.