Tallinn in May is late Nordic-Baltic spring — 15°C / 59°F afternoons, 5°C / 41°F mornings, 7 rain days. Daylight 17h 5m, white-night season starting; UNESCO Old Town at peak walking weather.
Tallinn in May runs Nordic-Baltic late spring building toward Estonian summer. Estonian Weather Service (Riigi Ilmateenistus) Tallinn-Harku station data put afternoon highs at 15°C / 59°F and overnight lows at 5°C / 41°F with 7 rain days. UV index 4-5, humidity 75%. Daylight stretches to 17h 5m. The 10°C / 18°F daily swing demands warm layers. The dressing register reads medieval-Hanseatic UNESCO Old Town with Estonian-Nordic minimalist contemporary register layered on top — the heritage 13th-century Hanseatic League city walls (the most-intact medieval town walls in Northern Europe, 1.85km / 1.15 miles preserved), Town Hall Square (Raekoja plats, the heritage Old Town center, hosts Christmas Market December and summer cafés May-August). Estonian Old Town walking is uneven: cobblestones throughout, slippery in rain, hill climbs to Toompea (the heritage Upper Town with Alexander Nevsky Cathedral, Toompea Castle, and the Kiek-in-de-Kök tower viewing platform). Local Estonian heritage: Reet Aus (Tallinn upcycled couture since 1995 — the most-recognized Estonian designer, the heritage Estonian sustainable-fashion pioneer), Liivi Leppik knitwear, Tanel Veenre jewelry (the heritage Estonian art jeweler, sea-glass + amber + silver), Aldo Järvsoo, Kärt Ojavee textile, plus the heritage Estonian wool-knit Muhu and Kihnu island sweaters, Saaremaa juniper-wood crafts (the heritage Estonian island woodwork). Estonian Song Festival (Laulupidu, every 5 years, the heritage 1869-founded national choral festival at Kalev Stadium; the next is 2027). Daylight 18h 30m on summer solstice; sauna culture shared with Finland. Cooler than Stockholm and Copenhagen.
Tallinn May is late Nordic-Baltic spring — UNESCO Old Town cobblestones at peak walking weather, the heritage 13th-century Hanseatic Town Hall Square (Raekoja plats) cafés opening, daylight stretching to 17h 5m. Wool sweater + leather sneakers + rain shell + Reet Aus.
Wool sweater or merino base + cotton tee · tailored trousers or dark denim · leather sneakers · warm rain shell · sunglasses · crossbody · water bottle. Coffee at Reval Café (the heritage Tallinn Old Town café institution) 8:30am, Town Hall Square (Raekoja plats) 9:30am, Toompea + Alexander Nevsky Cathedral 11:00am.
Tailored trousers · cotton button-down + Reet Aus piece or Tanel Veenre jewelry · cardigan + packable down jacket · leather low boots · crossbody. Dinner at Restaurant 180° by Matthias Diether (2-Michelin) or NOA (the heritage Tallinn-Pirita modern Estonian) 19:00; Iglupark sauna + Baltic-sea-swim after 21:00.
Per Estonian Weather Service (Riigi Ilmateenistus) Tallinn-Harku station data: average daily high 15°C (59°F), low 5°C (41°F), 7 rain days totalling 38mm. Late Nordic-Baltic spring building toward summer. UV index 4-5. Daylight 17h 5m (the heritage Estonian white-night season starting; June 21 solstice peaks at 18h 30m). Humidity 75%. The 10°C / 18°F diurnal swing demands warm layers. Tallinn cooler than Stockholm and Copenhagen by 1-2°C; warmer than Reykjavik and Helsinki summer.
Tallinn Old Town (Vanalinn — the heritage 13th-century Hanseatic League city, UNESCO World Heritage since 1997 — the most-intact medieval town walls in Northern Europe, 1.85km / 1.15 miles of preserved 13th-15th century walls; the heritage Toompea Upper Town + the lower-town Old Town divided by the heritage Pikk Jalg + Lühike Jalg streets; the heritage 1404-completed Town Hall (Raekoja, the only intact Gothic town hall in Northern Europe) on Town Hall Square (Raekoja plats); the heritage Alexander Nevsky Cathedral 1900 on Toompea; the heritage Kiek-in-de-Kök tower viewing platform; the heritage Town Wall Walk through 9 of 26 surviving medieval towers) is the recognized Tallinn cultural heritage. The recognized Old Town walking circuit: Town Hall Square (Raekoja plats — start at the heritage Old Town café) → Pikk street (the heritage merchant-house street, Marius Pikk 18 Tanel Veenre flagship) → Toompea hill via Pikk Jalg (the heritage Long Leg street, the recognized lower-to-upper-town climb) → Alexander Nevsky Cathedral + Toompea Castle + Estonian Parliament → Kiek-in-de-Kök tower viewing platform + Town Wall Walk → return via Lühike Jalg (the heritage Short Leg street). Allow 4-6 hours. Pack: leather sneakers + cotton tee + wool sweater + rain shell + crossbody + camera. Skip stilettos absolutely.
Yes — the heritage Helsinki-Tallinn ferry route (the recognized Baltic-Sea-crossing 80km / 50 miles, 2 hours, daily) is the most-cited Tallinn day-trip or transit-add-on. The recognized ferry operators: Tallink (the heritage Estonian-Finnish ferry operator, the recognized Megastar + MyStar fast-ferries, 2 hours each way, €25-45 round-trip — the most-cited Helsinki-Tallinn route); Eckerö Line (the heritage Finnish-Estonian ferry operator, 2 hours each way, €20-40 round-trip); Viking Line (the heritage Finnish ferry operator, 2.5 hours each way, €25-45 round-trip); Linda Line (smaller hydrofoil, 90 minutes each way, €30-50 round-trip — verify season May-September). Strategy: day-trip from Helsinki (08:00 Helsinki-Tallinn ferry, 18:00 return) for the heritage Old Town visit + lunch + light shopping; or longer-stay (2-3 nights) for the heritage Tallinn-extended visit + the heritage Saaremaa island day-trip. Pack: layered cotton + wool sweater + leather sneakers + warm rain shell + cardigan + crossbody + Estonian-Tallinn cash (euros — Estonia uses euros since 2011) + camera. Skip the ferry without booking 2-4 weeks ahead in May-September peak.
Reet Aus (Tallinn upcycled couture since 1995 — the most-recognized Estonian designer, the heritage Estonian sustainable-fashion pioneer, the recognized international upcycled-fashion innovator) is the recognized Tallinn design heritage. The flagship: Reet Aus Studio (Telliskivi 60a/3, Telliskivi Creative City — the heritage 1870s railway depot reborn as Tallinn's contemporary creative quarter; the recognized Reet Aus showroom + atelier, with the recognized Reet Aus + UPMADE certification — the heritage upcycled-fashion certification system Reet Aus founded). Reet Aus pieces: cotton + linen + wool dresses + tops + jackets + accessories ($60-300 — the heritage upcycled-Estonian-textile signature, each piece from textile-manufacturing waste); the recognized Reet Aus eveningwear + the heritage Reet Aus + Estonian-Songer-Festival traditional wool-knit collaboration. Other Estonian-design destinations in Tallinn: Tanel Veenre (the heritage Estonian art jeweler, flagship at Pikk 21 Old Town); Liivi Leppik knitwear; Aldo Järvsoo; Kärt Ojavee textile (Telliskivi Creative City); the heritage Saaremaa juniper-wood crafts at the Tallinn Old Town Estonian-craft shops; the heritage Estonian wool-knit Muhu + Kihnu island sweaters at the heritage Müürivahe street wool-sweater stalls (the recognized Tallinn Old Town wool-sweater wall — open-air market since the 1990s on the heritage Müürivahe street). Pack: leather sneakers + crossbody + Reet Aus shopping list + Telliskivi Creative City day-ticket.
Restaurant 180° by Matthias Diether (the heritage 2-Michelin modern Estonian, since 2014 — the recognized Tallinn fine dining, the most-cited Tallinn-Estonia tasting menu); NOA (Ranna tee 3, Pirita — the heritage Tallinn-Pirita modern Estonian, the recognized Estonian-coastal-fine-dining + the heritage Pirita waterfront-and-Old-Town view); Lee (Suur-Karja 8 — the heritage 1-Michelin modern Estonian by Janno Lepik); the heritage Restaurant Tchaikovsky (Vene 9 — the heritage Hotel Telegraaf 19th-century Russian-Estonian opulent fine dining); the heritage Olde Hansa (Vana turg 1 — the heritage medieval-themed restaurant on Town Hall Square, the recognized Tallinn-Old-Town tourist-medieval-tasting destination); the heritage III Draakon (Town Hall Square Raekoja plats — the heritage medieval pub with the heritage 14th-century recipes); the heritage Vanaema Juures (Rataskaevu 10/12 — the heritage Estonian grandmother's cooking, traditional Estonian dishes); the heritage Reval Café (the heritage Tallinn Old Town café institution); the heritage Telliskivi Creative City craft-beer + restaurant cluster (the heritage Estonian craft-beer + contemporary restaurant + design-shop quarter — recognized Tallinn evening register). Pack: tailored wool-blend trousers + cotton button-down + Reet Aus piece + Tanel Veenre jewelry + light cardigan + leather sneakers or low boots + crossbody. Estonian dinner 17:30-21:30 (peak 19:00-21:00).