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Season 2004

Every heat event the pipeline tracked between 2004-05-01 and 2004-09-30, with how each one grew, peaked and moved. Anomalies are against the 1991–2020 baseline.

Season at a glance

Events tracked
15
Total heat burden
29.86 Mkm²·days
Longest
15days (#8)
Hottest
+16.6°C (#1)
With a heat dome
8of 15 events

A heat dome is the stricter object: a tracked heat event with a closed 500 hPa anticyclone whose influence cap overlies it, after Loikith et al. (2026). Most heatwaves are not domes, so the label is a finding and not a synonym.

ERA5 daily maximum 2 m temperature over land, against the 1991–2020 climatology (p90 in a centred 15-day window). A heatwave cell is Tx above p90 on at least 3 consecutive days.

When the events ran

MayJunJulAugSep#110 d · +16.6 °C#26 d · +10.3 °C#38 d · +11.9 °C#48 d · +10.9 °C#514 d · +14.3 °C#610 d · +15.0 °C#76 d · +7.6 °C#815 d · +12.4 °C#96 d · +10.5 °C#105 d · +12.5 °C#114 d · +8.8 °C#128 d · +9.5 °C#137 d · +8.1 °C#1413 d · +10.8 °C#158 d · +12.5 °C2004-05-01 → 2004-09-30; bar colour is peak anomaly (+4 to +16 °C); filled dot = heat dome, hollow = no overlying high

Overlapping bars are concurrent events in different places, not one event counted twice: each is a separately labelled cluster of contiguous heatwave cells.

How each event evolved

Event #1 — 2004-05-02 → 2004-05-11 10 daysheat dome · 6/10 d · Z500 +303 m

peak 1.68 M km² on 2004-05-07 · max +16.6 °C · mean +10.0 °C · burden 7.65 M km²·d · drift 1095 km (63.1 N 26.7 E → 60.3 N 6.7 E)

1.7Mkm²+16.6+0.0 °C2004-05-022004-05-11peak 2004-05-07centroid drift · 15.3° box

Event #15 — 2004-09-23 → 2004-09-30 8 daysheat dome · 5/8 d · Z500 +164 m

peak 1.27 M km² on 2004-09-28 · max +12.5 °C · mean +6.8 °C · burden 5.94 M km²·d · drift 479 km (41.7 N 44.3 E → 39.8 N 39.2 E)

1.3Mkm²+12.5+0.0 °C2004-09-232004-09-30peak 2004-09-28centroid drift · 5.7° box

Event #8 — 2004-07-30 → 2004-08-13 15 daysheat dome · 9/15 d · Z500 +268 m

peak 458k km² on 2004-08-09 · max +12.4 °C · mean +7.2 °C · burden 3.94 M km²·d · drift 1162 km (68.9 N 20.1 E → 60.2 N 6.3 E)

458kkm²+12.4+0.0 °C2004-07-302004-08-13peak 2004-08-09centroid drift · 11.7° box

Event #12 — 2004-09-03 → 2004-09-10 8 dayshigh on 3/8 d only

peak 401k km² on 2004-09-05 · max +9.5 °C · mean +6.5 °C · burden 1.92 M km²·d · drift 274 km (51.2 N 4.8 E → 49.5 N 2.0 E)

401kkm²+9.5+0.0 °C2004-09-032004-09-10peak 2004-09-05centroid drift · 4.2° box

Event #3 — 2004-06-05 → 2004-06-12 8 daysheat dome · 7/8 d · Z500 +145 m

peak 501k km² on 2004-06-09 · max +11.9 °C · mean +7.7 °C · burden 1.64 M km²·d · drift 1202 km (48.5 N -3.7 E → 45.0 N 11.3 E)

501kkm²+11.9+0.0 °C2004-06-052004-06-12peak 2004-06-09centroid drift · 12.8° box

Event #14 — 2004-09-18 → 2004-09-30 13 dayshigh on 4/13 d only

peak 299k km² on 2004-09-22 · max +10.8 °C · mean +6.4 °C · burden 1.62 M km²·d · drift 233 km (38.0 N -5.8 E → 40.0 N -6.5 E)

299kkm²+10.8+0.0 °C2004-09-182004-09-30peak 2004-09-22centroid drift · 4.7° box

Event #10 — 2004-08-20 → 2004-08-24 5 daysheat dome · 4/5 d · Z500 +182 m

peak 434k km² on 2004-08-22 · max +12.5 °C · mean +8.6 °C · burden 1.43 M km²·d · drift 470 km (54.1 N 41.5 E → 50.1 N 43.9 E)

434kkm²+12.5+0.0 °C2004-08-202004-08-24peak 2004-08-22centroid drift · 4.9° box

Event #4 — 2004-06-25 → 2004-07-02 8 daysheat dome · 5/8 d · Z500 +115 m

peak 279k km² on 2004-06-29 · max +10.9 °C · mean +6.8 °C · burden 1.27 M km²·d · drift 6 km (37.3 N -7.4 E → 37.3 N -7.5 E)

279kkm²+10.9+0.0 °C2004-06-252004-07-02peak 2004-06-29centroid drift · 2.9° box

Event #2 — 2004-05-15 → 2004-05-20 6 daysheat dome · 4/6 d · Z500 +241 m

peak 335k km² on 2004-05-18 · max +10.3 °C · mean +7.0 °C · burden 1.18 M km²·d · drift 834 km (41.1 N -8.9 E → 45.4 N -0.4 E)

335kkm²+10.3+0.0 °C2004-05-152004-05-20peak 2004-05-18centroid drift · 7.7° box

Event #5 — 2004-06-27 → 2004-07-10 14 dayshigh on 5/14 d only

peak 127k km² on 2004-07-01 · max +14.3 °C · mean +9.8 °C · burden 732k km²·d · drift 185 km (66.5 N 44.5 E → 68.2 N 44.4 E)

127kkm²+14.3+0.0 °C2004-06-272004-07-10peak 2004-07-01centroid drift · 5.1° box

Event #11 — 2004-08-31 → 2004-09-03 4 daysno overlying high

peak 231k km² on 2004-08-31 · max +8.8 °C · mean +7.0 °C · burden 692k km²·d · drift 276 km (62.0 N 36.9 E → 61.5 N 31.8 E)

231kkm²+8.8+0.0 °C2004-08-312004-09-03peak 2004-08-31centroid drift · 3.0° box

Event #6 — 2004-06-30 → 2004-07-09 10 daysno overlying high

peak 124k km² on 2004-07-02 · max +15.0 °C · mean +9.3 °C · burden 504k km²·d · drift 143 km (66.5 N 37.1 E → 67.4 N 39.6 E)

124kkm²+15.0+0.0 °C2004-06-302004-07-09peak 2004-07-02centroid drift · 3.3° box

Event #9 — 2004-08-02 → 2004-08-07 6 daysheat dome · 4/6 d · Z500 +224 m

peak 106k km² on 2004-08-05 · max +10.5 °C · mean +8.0 °C · burden 488k km²·d · drift 62 km (65.5 N 41.7 E → 65.1 N 42.5 E)

106kkm²+10.5+0.0 °C2004-08-022004-08-07peak 2004-08-05centroid drift · 1.3° box

Event #7 — 2004-07-04 → 2004-07-09 6 dayshigh on 2/6 d only

peak 121k km² on 2004-07-07 · max +7.6 °C · mean +4.4 °C · burden 465k km²·d · drift 386 km (36.9 N 37.2 E → 35.2 N 40.9 E)

121kkm²+7.6+0.0 °C2004-07-042004-07-09peak 2004-07-07centroid drift · 3.8° box

Event #13 — 2004-09-03 → 2004-09-09 7 dayshigh on 3/7 d only

peak 101k km² on 2004-09-05 · max +8.1 °C · mean +5.0 °C · burden 400k km²·d · drift 231 km (52.6 N -0.4 E → 51.3 N -3.1 E)

101kkm²+8.1+0.0 °C2004-09-032004-09-09peak 2004-09-05centroid drift · 2.1° box

Filled area is the event footprint in km² (left axis); the solid line is the peak anomaly inside it and the dashed line the mean (right axis). The small panel is the centroid path, circles sized by area and the ring marking day one. Drift is the straight-line start-to-end distance, so a dome that wandered and returned reports a small number.

Pipeline figures, 2004

Extent through the season

heatwave extent 2004

Footprints and tracks

heatwave events 2004