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Data study

The hottest towns for conservatories in England

We ran two years of hourly weather for 104 English towns through one typical south facing conservatory. Under a polycarbonate roof, Hounslow comes top with 1,501 waking hours a year above 25°C; Buxton is lowest at 949. With an insulated panel roof, even the worst town drops to 482.

Download the CSVComfort Calendar
Top 10: waking hours above 25°C a year, polycarbonate roof

All 104 towns, ranked

Modelled waking hours a year (8am to 10pm), south facing room, 2024 and 2025 weather
Town Rank Region Over 25°C, polycarbonate Over 25°C, glass Over 25°C, panels Over 30°C, polycarbonate Hottest hour, polycarbonate
Hounslow 1 Greater London 1,501 1,642 481 721 49°C
Twickenham 2 Greater London 1,496 1,642 475 717 49°C
Kingston upon Thames 3 Greater London 1,496 1,642 475 717 49°C
Hornchurch 4 Greater London 1,494 1,635 465 702 50°C
Walthamstow 5 Greater London 1,493 1,641 482 714 49°C
Ipswich 6 East Anglia and Hertfordshire 1,492 1,631 414 717 46°C
Bexleyheath 7 Greater London 1,490 1,627 467 705 50°C
Woking 8 Thames Valley and Surrey 1,476 1,618 449 695 49°C
Maidenhead 9 Thames Valley and Surrey 1,468 1,621 447 694 48°C
Chingford 10 Greater London 1,466 1,613 447 687 49°C
Eltham 11 Greater London 1,461 1,597 442 685 49°C
Wembley 12 Greater London 1,460 1,608 447 688 49°C
Braintree 13 East Anglia and Hertfordshire 1,459 1,608 425 686 46°C
Ely 14 East Anglia and Hertfordshire 1,457 1,595 407 664 45°C
Wokingham 15 Thames Valley and Surrey 1,457 1,593 429 683 48°C
Ruislip 16 Greater London 1,454 1,594 440 682 48°C
Uxbridge 17 Greater London 1,454 1,594 440 682 48°C
Brentwood 18 East Anglia and Hertfordshire 1,447 1,598 411 670 48°C
Guildford 19 Thames Valley and Surrey 1,440 1,580 399 668 47°C
Harlow 20 East Anglia and Hertfordshire 1,437 1,582 416 667 47°C
Tunbridge Wells 21 Thames Valley and Surrey 1,436 1,570 376 660 49°C
Sutton 22 Greater London 1,434 1,582 412 665 49°C
Bury St Edmunds 23 East Anglia and Hertfordshire 1,431 1,587 404 664 46°C
St Neots 24 East Anglia and Hertfordshire 1,427 1,563 408 641 47°C
Norwich 25 East Anglia and Hertfordshire 1,414 1,557 370 634 45°C
Saffron Walden 26 East Anglia and Hertfordshire 1,411 1,558 390 638 46°C
Abingdon 27 Thames Valley and Surrey 1,407 1,548 385 628 47°C
Weston-super-Mare 28 West Country 1,407 1,564 308 638 47°C
Letchworth Garden City 29 East Anglia and Hertfordshire 1,401 1,541 372 626 47°C
Orpington 30 Greater London 1,398 1,544 373 633 49°C
Bridgwater 31 West Country 1,397 1,549 302 623 47°C
Tewkesbury 32 West Country 1,396 1,538 355 590 48°C
Thame 33 Thames Valley and Surrey 1,394 1,540 373 618 47°C
Didcot 34 Thames Valley and Surrey 1,388 1,525 372 617 46°C
Clevedon 35 West Country 1,387 1,556 327 613 49°C
Marlow 36 Thames Valley and Surrey 1,385 1,535 371 620 47°C
Wallingford 37 Thames Valley and Surrey 1,381 1,530 365 615 46°C
Basingstoke 38 Thames Valley and Surrey 1,374 1,530 351 616 47°C
Salisbury 39 West Country 1,374 1,532 352 614 47°C
Hitchin 40 East Anglia and Hertfordshire 1,372 1,511 357 609 47°C
Henley-on-Thames 41 Thames Valley and Surrey 1,366 1,525 355 609 47°C
Rushden 42 East Midlands 1,365 1,506 356 584 47°C
Stamford 43 East Midlands 1,365 1,501 356 588 47°C
Droitwich Spa 44 West Midlands 1,361 1,505 327 571 48°C
Harpenden 45 East Anglia and Hertfordshire 1,359 1,509 354 607 46°C
Yate 46 West Country 1,357 1,508 317 602 48°C
Buckingham 47 Thames Valley and Surrey 1,347 1,500 342 583 47°C
Hemel Hempstead 48 East Anglia and Hertfordshire 1,346 1,481 332 589 47°C
Exeter 49 West Country 1,346 1,504 274 579 46°C
Taunton 50 West Country 1,342 1,500 292 591 47°C
Malvern 51 West Midlands 1,341 1,498 320 559 48°C
Trowbridge 52 West Country 1,337 1,491 328 592 48°C
Devizes 53 West Country 1,332 1,479 318 581 47°C
Newark-on-Trent 54 East Midlands 1,331 1,475 328 554 46°C
Beverley 55 Yorkshire and the Humber 1,325 1,480 280 551 45°C
Long Eaton 56 East Midlands 1,312 1,446 311 527 47°C
Keynsham 57 West Country 1,312 1,472 296 573 48°C
Grantham 58 East Midlands 1,311 1,458 314 539 46°C
Selby 59 Yorkshire and the Humber 1,303 1,448 295 530 46°C
Malmesbury 60 West Country 1,301 1,459 298 564 47°C
Bedworth 61 West Midlands 1,299 1,450 303 518 47°C
Frome 62 West Country 1,299 1,457 293 557 48°C
Hereford 63 West Midlands 1,295 1,445 281 531 47°C
Ilkeston 64 East Midlands 1,294 1,431 313 528 47°C
Doncaster 65 Yorkshire and the Humber 1,291 1,435 303 519 46°C
Market Harborough 66 East Midlands 1,284 1,422 297 511 47°C
Pontefract 67 Yorkshire and the Humber 1,281 1,415 274 508 46°C
Stourbridge 68 West Midlands 1,280 1,428 290 507 48°C
Melton Mowbray 69 East Midlands 1,273 1,418 286 500 46°C
Hucknall 70 East Midlands 1,271 1,397 286 514 47°C
Burton upon Trent 71 West Midlands 1,269 1,415 287 500 47°C
York 72 Yorkshire and the Humber 1,267 1,414 254 498 45°C
Dudley 73 West Midlands 1,264 1,405 291 493 49°C
Halesowen 74 West Midlands 1,264 1,405 291 493 49°C
Coalville 75 East Midlands 1,260 1,402 268 487 46°C
Worksop 76 East Midlands 1,260 1,408 281 490 46°C
West Bromwich 77 West Midlands 1,250 1,396 283 485 48°C
Southport 78 North West 1,239 1,391 184 449 45°C
Sheffield 79 Yorkshire and the Humber 1,236 1,376 286 485 47°C
Rotherham 80 Yorkshire and the Humber 1,235 1,376 275 483 46°C
Walsall 81 West Midlands 1,234 1,391 277 472 48°C
Uttoxeter 82 West Midlands 1,225 1,364 241 457 47°C
Wetherby 83 Yorkshire and the Humber 1,224 1,376 227 471 45°C
Cannock 84 West Midlands 1,220 1,367 249 462 47°C
Altrincham 85 North West 1,216 1,377 242 458 47°C
Sale 86 North West 1,216 1,377 242 458 47°C
Widnes 87 North West 1,213 1,357 220 430 48°C
Nantwich 88 North West 1,209 1,361 227 445 47°C
St Helens 89 North West 1,205 1,356 213 432 48°C
Knutsford 90 North West 1,204 1,342 223 439 47°C
Runcorn 91 North West 1,197 1,354 213 421 47°C
Northwich 92 North West 1,192 1,334 203 417 47°C
Scarborough 93 Yorkshire and the Humber 1,187 1,354 158 416 42°C
Preston 94 North West 1,182 1,338 191 431 45°C
Belper 95 East Midlands 1,171 1,329 227 437 46°C
Newcastle-under-Lyme 96 West Midlands 1,168 1,315 213 412 47°C
Barnsley 97 Yorkshire and the Humber 1,140 1,296 213 416 46°C
Wigan 98 North West 1,116 1,255 172 373 45°C
Keighley 99 Yorkshire and the Humber 1,083 1,237 162 378 44°C
Halifax 100 Yorkshire and the Humber 1,067 1,215 158 363 44°C
Lancaster 101 North West 1,058 1,198 119 339 43°C
Ilkley 102 Yorkshire and the Humber 1,043 1,187 137 347 44°C
Bolton 103 North West 1,025 1,168 132 321 44°C
Buxton 104 East Midlands 949 1,096 105 277 44°C

What the table shows

The warmest, sunniest parts of the south east and London put the most too-warm hours into a polycarbonate conservatory, but the spread is narrower than people expect: even the cooler northern and hill towns give the same room close to a thousand waking hours above 25°C. Sunshine through the roof does most of the work, and England gets plenty of bright days that are not hot outside.

The panel roof column is the point. Taking the sun off the roof cuts too-warm hours by 76% on average, and the hours above 30°C from 556 to 34.

Method in one paragraph

One room: 14 m² floor (4.0 m by 3.5 m), three glazed sides, south facing. One heat balance stepped every 15 minutes, hourly Open-Meteo weather for every hour of 2024 and 2025 at each town's coordinates, and doors opened once the room passes 25°C. The full method, inputs and limits are on how we model it. Weather data by Open-Meteo.com (CC BY 4.0).

Use it

Journalists, bloggers and councils are welcome to use the table under CC BY 4.0: credit Warmlid and link to this page. The CSV has coordinates, peaks and heat use too. Questions about the data go to hello@warmlid.co.uk.

Questions people ask

Why do London towns top the table?

They are warmer and sunnier in summer than most of England, and the city holds its heat at night, so a conservatory starts each day warmer. Under polycarbonate that adds up to the most too-warm hours.

Why is a northern town still so high?

Sunshine, not just air temperature, overheats a conservatory. A bright spring day at 14°C outside can still push a shut polycarbonate room past 25°C anywhere in England.

Can I use the table in an article?

Yes. It is free under CC BY 4.0: credit Warmlid and link to this page. The CSV download has every column.

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