It usually starts to feel noticeably warmer in the UK from late March into April, with the most reliable warmer weather arriving in May and June as spring turns into summer.

When it gets warmer in the UK

  • Early signs of warmth:
    From late March to April , average temperatures start to climb as meteorological spring (1 March–31 May) gets going, and daylight increases. You’ll still get chilly, wet spells, but more mild, sunny days begin to creep in.
  • Consistently milder weather:
    May is often when it begins to feel “properly” mild for many people, with more days in the mid-teens Celsius and longer, brighter evenings. By this point, frosts are less common away from northern and highland areas.
  • Warmest period:
    June to August is the UK summer and the climatologically warmest period, with typical daytime highs in the high teens to low/mid‑20s °C in many areas, and hotter spells during heatwaves. Recent years, including 2025, have seen unusually warm springs and very hot summers due to a warming climate.

Regional differences

  • South of England: Warms up earliest and most, often feeling springlike from late March and reaching comfortable T‑shirt weather more often in May and June.
  • Midlands, Wales, Northern Ireland: A little later and slightly cooler than the far south, but follow a similar pattern into late spring and summer.
  • Scotland and northern areas: Tend to lag by a few weeks, with cooler conditions in March–April and a shorter, later-feeling warm season.

Forum-style perspective

If you ask people on UK forums, “warm” isn’t just about the thermometer. Many describe anything around 15–18°C with sunshine as “nice and warm”, especially after a cold winter, while others feel too hot by the time it’s getting close to 20°C. The classic British experience is stepping out in a T‑shirt because the sun is shining, only to discover it’s still freezing and going back in for a jumper.

Quick month‑by‑month feel

  • March: Still changeable; more light, occasional mild days, but can feel cold and damp.
  • April: Mix of showers and brighter spells; more days that feel pleasantly cool‑mild.
  • May: Often the first month that feels generally mild and “springlike”, with some early warm days.
  • June–August: Main warm season; more reliable T‑shirt weather, with hot spells in some years.

So, if you’re waiting for it to “get warmer” in the UK: expect hints of warmth from late March, a generally milder feel through April, and genuinely warm, summer‑like conditions most reliably from May into June.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.