Bielefeld, North Rhine Westphalia, Germany Historical Air Quality Analysis
Dive into detailed Air Quality Insights with historical data, monthly patterns, and yearly trends at your fingertips!
September Air Quality Analysis
Bielefeld, North Rhine Westphalia, Germany
AQI Trends: Highest and Lowest
Same Day Analysis (18th September ):
On this day, AQI across the 5 years varied significantly: 2025 ranks 4th highest AQI at 20 of Good air quality, showing improvement over 2024, 2023 and 2021 on the same day.
Download 2024 Annual Data
World Air Quality Report

Day & Night AQI Trend: 19th Sep - 20th Sep 2025
Bielefeld, North Rhine Westphalia, Germany
6 AM19th Sep 2025
8 PM
5 AM20th Sep 2025
AQI
AQI
27AQI
23AQI
In the last 24 hours,
Bielefeld's AQI reached its highest point of 27 at 9 AM during the Night, while the lowest point, undefined, was recorded at 5 AM during the Night between 19th Sep and 20th Sep 2025.
Day & Night AQI Trend : Aug - Sep 2025
Bielefeld, North Rhine Westphalia, Germany
18°C12/23°C
14°C10/17°C
14°C11/18°C
15°C9/20°C
16°C8/23°C
20°C12/28°C
20°C14/27°C
20°C15/25°C
19°C14/25°C
18°C13/22°C
19°C14/24°C
18°C15/21°C
18°C14/22°C
20°C15/24°C
20°C16/25°C
17°C14/22°C
17°C11/23°C
19°C14/25°C
18°C14/24°C
17°C13/22°C
15°C12/20°C
16°C13/21°C
15°C11/19°C
14°C11/19°C
14°C10/19°C
18°C14/21°C
14°C12/17°C
14°C11/18°C
18°C15/22°C
--°C/°C
--°C/°C
24AQI
22AQI
24AQI
22AQI
2025 Days Vs Air Quality
Bielefeld, North Rhine Westphalia, Germany
75%
195
23%
60
2%
6
Total number of days with different AQI categories in last 262 days in 2025 (103 days remaining)
Under WHO’s Safe Air Quality Limits: 75%
Health Risk Level:
Low
In 2025, 75% of 262 days were within WHO’s safe air quality limits. The risk of health issues is Low, but the long-term effects, especially on vulnerable individuals, remain uncertain.
Annual Air Quality Insights
Bielefeld, North Rhine Westphalia, Germany
AQI levels in 2025
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
41AQI
29AQI
29AQI
41AQI
46AQI
24AQI
25AQI
26AQI
26AQI
33AQI
41AQI
34AQI
47AQI
58AQI
58AQI
47AQI
45AQI
50AQI
73AQI
70AQI
84AQI
75AQI
55AQI
30AQI
23AQI
27AQI
24AQI
25AQI
23AQI
23AQI
34AQI
62AQI
69AQI
69AQI
75AQI
68AQI
59AQI
50AQI
72AQI
101AQI
115AQI
115AQI
97AQI
136AQI
98AQI
65AQI
61AQI
59AQI
61AQI
60AQI
60AQI
70AQI
62AQI
48AQI
32AQI
39AQI
52AQI
36AQI
46AQI
51AQI
54AQI
55AQI
65AQI
69AQI
65AQI
59AQI
70AQI
99AQI
113AQI
117AQI
62AQI
49AQI
33AQI
41AQI
52AQI
28AQI
29AQI
45AQI
58AQI
59AQI
61AQI
68AQI
67AQI
85AQI
72AQI
41AQI
63AQI
59AQI
33AQI
28AQI
28AQI
28AQI
42AQI
51AQI
41AQI
18AQI
21AQI
25AQI
49AQI
46AQI
54AQI
55AQI
37AQI
50AQI
58AQI
34AQI
37AQI
24AQI
28AQI
56AQI
59AQI
40AQI
55AQI
43AQI
53AQI
54AQI
26AQI
32AQI
42AQI
32AQI
40AQI
43AQI
40AQI
23AQI
21AQI
21AQI
30AQI
22AQI
22AQI
21AQI
23AQI
19AQI
24AQI
32AQI
32AQI
24AQI
35AQI
37AQI
28AQI
27AQI
30AQI
32AQI
20AQI
19AQI
22AQI
24AQI
27AQI
17AQI
18AQI
24AQI
37AQI
32AQI
41AQI
30AQI
39AQI
23AQI
17AQI
16AQI
16AQI
24AQI
51AQI
44AQI
43AQI
49AQI
51AQI
49AQI
33AQI
34AQI
37AQI
36AQI
26AQI
28AQI
29AQI
31AQI
24AQI
25AQI
27AQI
26AQI
29AQI
28AQI
26AQI
24AQI
33AQI
33AQI
24AQI
22AQI
21AQI
19AQI
20AQI
22AQI
26AQI
23AQI
21AQI
28AQI
30AQI
40AQI
28AQI
25AQI
30AQI
35AQI
34AQI
25AQI
21AQI
29AQI
29AQI
28AQI
29AQI
41AQI
27AQI
23AQI
21AQI
22AQI
24AQI
22AQI
21AQI
23AQI
24AQI
24AQI
27AQI
30AQI
39AQI
40AQI
34AQI
44AQI
55AQI
61AQI
63AQI
56AQI
39AQI
27AQI
26AQI
33AQI
28AQI
22AQI
21AQI
20AQI
20AQI
26AQI
35AQI
44AQI
29AQI
19AQI
19AQI
17AQI
18AQI
17AQI
19AQI
19AQI
21AQI
22AQI
24AQI
39AQI
37AQI
24AQI
18AQI
18AQI
18AQI
15AQI
19AQI
20AQI
20AQI
41AQI
69AQI
60AQI
41AQI
27AQI
32AQI
27AQI
32AQI
21AQI
No. of days
202539AQI
Highest AQI recorded in
February69AQI
Lowest AQI recorded in
September21AQI
202436AQI
Highest AQI recorded in
March52AQI
Lowest AQI recorded in
July29AQI
202336AQI
Highest AQI recorded in
February68AQI
Lowest AQI recorded in
November26AQI
202235AQI
Highest AQI recorded in
December54AQI
Lowest AQI recorded in
August22AQI
202127AQI
Highest AQI recorded in
June37AQI
Lowest AQI recorded in
January15AQI
202020AQI
Highest AQI recorded in
March28AQI
Lowest AQI recorded in
December15AQI
Most & Least Polluted Years Over the Last 6 Years
Bielefeld's annual 2025 AQI (39) shows an average percentage change of 34.9% (worsened AQI) compared to previous years: 2020 (20), 2021 (27), 2022 (35), 2023 (36), 2024 (36).