Figure 1.
Figure 2.
Figure 3.
Basic parameters of the stations included in the analysis and linear regression results
| Station | λ | ϕ | Altitude (m a.s.l.) | TNs/10 years growth |
|---|---|---|---|---|
| Warsaw-Bielany | 20°57′48″E | 52°16′53″N | 98 | 0.49 |
| Warsaw-Obserwatorium | 21°01′43″E | 52°13′04″N | 110 | 0.37 |
| Warsaw-Okęcie | 20°57′40″E | 52°09′46″N | 106 | 0.33 |
| Legionowo | 20°57′22″E | 52°24′28″N | 94 | 0.32 |
Cases of simultaneous occurrence of TNs at all stations along with recorded minimum air temperatures (in °C)_ The highest temperature of individual nights is marked in red
| Case number | Date | Warsaw-Bielany | Warsaw-Obserwatorium | Warsaw-Okęcie | Legionowo | Max | Min | Temperature amplitude between synoptic stations |
|---|---|---|---|---|---|---|---|---|
| 1 | 16.07.1972 | 20.3 | 20.3 | 20.1 | 20.2 | 20.3 | 20.1 | 0.2 |
| 2 | 07.08.1994 | 20.5 | 20.2 | 20.2 | 20.1 | 20.5 | 20.1 | 0.4 |
| 3 | 08.06.1998 | 22.1 | 21.5 | 20.0 | 21.1 | 22.1 | 20.0 | 2.1 |
| 4 | 03.08.1998 | 21.2 | 20.0 | 20.5 | 20.2 | 21.2 | 20.0 | 1.2 |
| 5 | 16.07.2010 | 21.5 | 21.0 | 21.6 | 20.2 | 21.6 | 20.2 | 1.4 |
| 6 | 18.07.2010 | 20.8 | 21.7 | 20.9 | 21.1 | 21.7 | 20.8 | 0.9 |
| 7 | 23.07.2010 | 21.7 | 20.8 | 20.0 | 20.4 | 21.7 | 20.0 | 1.7 |
| 8 | 29.07.2013 | 22.7 | 21.2 | 22.1 | 21.6 | 22.7 | 21.2 | 1.5 |
| 9 | 30.07.2013 | 20.0 | 20.8 | 21.0 | 21.0 | 21.0 | 20.0 | 1.0 |
| 10 | 05.08.2013 | 20.3 | 21.1 | 20.8 | 20.1 | 21.1 | 20.1 | 1.0 |
| 11 | 09.08.2013 | 20.9 | 21.8 | 21.4 | 20.9 | 21.8 | 20.9 | 0.9 |
| 12 | 07.08.2015 | 20.2 | 20.8 | 21.1 | 20.6 | 21.1 | 20.2 | 0.9 |
| 13 | 09.08.2015 | 22.9 | 22.4 | 22.8 | 22.5 | 22.9 | 22.4 | 0.5 |
| 14 | 13.08.2015 | 20.7 | 21.0 | 20.8 | 20.9 | 21.0 | 20.7 | 0.3 |
| 15 | 02.08.2017 | 23.2 | 21.8 | 21.7 | 24.0 | 24.0 | 21.7 | 2.3 |
| 16 | 04.08.2017 | 20.4 | 21.0 | 20.6 | 20.1 | 21.0 | 20.1 | 0.9 |
| 17 | 13.06.2019 | 22.9 | 20.3 | 21.2 | 21.3 | 22.9 | 20.3 | 2.6 |
| 18 | 16.06.2019 | 22.0 | 21.5 | 20.9 | 21.9 | 22.0 | 20.9 | 1.1 |
| 19 | 01.07.2019 | 22.9 | 22.9 | 22.4 | 22.2 | 22.9 | 22.2 | 0.7 |
| 20 | 17.08.2023 | 23.5 | 21.9 | 22.2 | 21.9 | 23.5 | 21.9 | 1.6 |
TNs presented by month in individual decades 1951–2020 and years 2021–2024
| Decades/Months | May | June | July | August | Total |
|---|---|---|---|---|---|
| 1951–1960 | 2 | 1 | 11 | 4 | 18 |
| 1961–1970 | 0 | 0 | 2 | 6 | 8 |
| 1971–1980 | 0 | 0 | 9 | 3 | 12 |
| 1981–1990 | 0 | 2 | 16 | 3 | 21 |
| 1991–2000 | 0 | 12 | 15 | 28 | 55 |
| 2001–2010 | 0 | 6 | 47 | 11 | 64 |
| 2011–2020 | 0 | 23 | 35 | 51 | 109 |
| 2021–2024 | 0 | 7 | 21 | 20 | 48 |
| Total | 2 | 51 | 156 | 126 | 335 |
| Percentage | 0.60 | 15.22 | 46.57 | 37.61 | 100.00 |
Number of TNs at individual stations over decades 1951–2020 and years 2021–2024 and their mean values
| Decades/Stations | 1951–1960 | 1961–1970 | 1971–1980 | 1981–1990 | 1991–2000 | 2001–2010 | 2011–2020 | 2021–2024 | Total | TNs mean/1 year |
|---|---|---|---|---|---|---|---|---|---|---|
| Warszawa-Bielany | 11 | 2 | 5 | 12 | 22 | 24 | 34 | 22 | 132 | 1.78 |
| Warszawa-Obserwatorium | 4 | 3 | 4 | 7 | 21 | 23 | 27 | 9 | 98 | 1.32 |
| Warszawa-Okęcie | 0 | 2 | 2 | 0 | 4 | 12 | 31 | 8 | 59 | 0.80 |
| Legionowo | 3 | 1 | 1 | 2 | 8 | 5 | 17 | 9 | 46 | 0.62 |
| Total | 18 | 8 | 12 | 21 | 55 | 64 | 109 | 48 | 335 | 4.53 |
| TNs mean/1 year | 1.80 | 0.80 | 1.20 | 2.10 | 5.50 | 6.40 | 10.90 | 12.00 | 4.53 |