Figure 1.

Figure 2.
![Duration of thermal spring for nine selected stations [days]Source: own study](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64724862215d2f6c89dc2e1e/j_mgrsd-2023-0041_fig_002.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251205%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251205T003805Z&X-Amz-Expires=3600&X-Amz-Signature=715a4ea464c5eae0358504e8fdc4d015e51aa08c937d4ebd89dac23c618fe44a&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 3.
![The mean values of seasonal air temperatures in 1951–2020 [°C]Source: own study](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64724862215d2f6c89dc2e1e/j_mgrsd-2023-0041_fig_003.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251205%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251205T003805Z&X-Amz-Expires=3600&X-Amz-Signature=5b325427f78c54be3e430cb495bfffaa109663b207f08d7d246fbaab9200e423&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 4.
![The mean values of spring air temperatures in 1951–2020 [°C]Source: own study](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64724862215d2f6c89dc2e1e/j_mgrsd-2023-0041_fig_004.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251205%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251205T003805Z&X-Amz-Expires=3600&X-Amz-Signature=0e00c1b68df83288856c554249cab8965c3a952f1a349da7d7a10730e71eaf3d&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 5.
![The mean values of autumn air temperatures in 1951–2020 [°C]Source: own study](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64724862215d2f6c89dc2e1e/j_mgrsd-2023-0041_fig_005.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251205%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251205T003805Z&X-Amz-Expires=3600&X-Amz-Signature=c19c69113f7d54c9a0a988f9a84ae3b76949245f8d7658ac81e390d42b7f80cf&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 6.
![The seasonal sum of precipitation for 1952–2020 [mm] Source: own study](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64724862215d2f6c89dc2e1e/j_mgrsd-2023-0041_fig_006.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251205%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251205T003805Z&X-Amz-Expires=3600&X-Amz-Signature=c350f1a1438c3cf57d175f6c06c6db596e0ee5974384baa94d90a8856ea9bdd5&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 7.
![The seasonal sum of winter precipitation in 1952–2020 [mm]Source: own study](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64724862215d2f6c89dc2e1e/j_mgrsd-2023-0041_fig_007.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251205%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251205T003805Z&X-Amz-Expires=3600&X-Amz-Signature=20f9ee401e75659bbc377637a215bfdcc560b062e1cdd6d64d21c1d53d4e9251&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 8.
![The seasonal sum of spring precipitation in 1951–2020 [mm]Source: own study](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/64724862215d2f6c89dc2e1e/j_mgrsd-2023-0041_fig_008.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251205%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251205T003805Z&X-Amz-Expires=3600&X-Amz-Signature=7b6e1c6ceb759184c8b92f2de7ff3767a48fa25f7bdfba920937549ef914387d&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 9.

Figure 10.

Figure 11.

Figure 12.

Figure 13.

The average differences between the seasonal precipitation for meteorological seasons and those of thermal and calendar seasons in 1951–2020 [mm]
| meteorological season | vs. thermal | vs. calendar |
|---|---|---|
| winter | +10 | −10 |
| spring | − 5 | + a dozen to several dozen |
| summer | − 1 to −5 | - several to − 20-odd |
| autumn | − 4 | - a dozen to − 20 |
The average differences between the temperatures of meteorological seasons and those of thermal and calendar seasons in 1951–2020 [°C]
| meteorological season | vs. thermal | vs. calendar |
|---|---|---|
| winter | +0.1 (West) to +0.4 (East) | +0.3 whole area |
| spring | +1.0 (West) to +2.5 (East) | +3–3.5 whole area |
| summer | +0.2 whole area | −0.5 whole area |
| autumn | −0.2 to −0.4 depending on the region | −3.0 whole area |
The coincidence of the beginning of the meteorological and thermal seasons, with up to five days’ variation (the number of occurrences between 1951 and 2020)
| station | spring | summer | autumn | winter | station | spring | summer | autumn | winter |
|---|---|---|---|---|---|---|---|---|---|
| BIAŁYSTOK | 12 | 53 | 60 | 68 | POZNAŃ | 27 | 57 | 51 | 68 |
| BIELSKO-BIAŁA | 33 | 52 | 51 | 65 | SANDOMIERZ | 25 | 57 | 46 | 69 |
| CHOJNICE | 15 | 53 | 63 | 68 | SIEDLCE | 18 | 58 | 55 | 68 |
| CZĘSTOCHOWA | 28 | 56 | 51 | 68 | SŁUBICE | 37 | 56 | 51 | 63 |
| GORZÓW | 30 | 58 | 48 | 68 | SUWAŁKI | 6 | 54 | 61 | 68 |
| JELENIA GÓRA | 27 | 45 | 66 | 68 | ŚWINOUJŚCIE | 29 | 47 | 45 | 63 |
| KALISZ | 25 | 56 | 46 | 68 | SZCZECIN | 32 | 55 | 49 | 65 |
| KIELCE | 23 | 53 | 53 | 68 | TARNÓW | 32 | 56 | 45 | 66 |
| KOSZALIN | 25 | 49 | 56 | 66 | TORUŃ | 25 | 57 | 52 | 68 |
| LUBLIN | 19 | 53 | 56 | 69 | WARSZAWA | 25 | 57 | 49 | 68 |
| ŁEBA | 12 | 40 | 55 | 67 | WŁODAWA | 18 | 59 | 52 | 69 |
| ŁÓDŹ | 21 | 56 | 52 | 68 | WROCŁAW | 33 | 57 | 45 | 67 |
| OLSZTYN | 17 | 53 | 55 | 68 | ZAKOPANE | 13 | 29 | 69 | 69 |
| OPOLE | 34 | 59 | 46 | 68 | ZIELONA GÓRA | 32 | 56 | 55 | 66 |
| PŁOCK | 23 | 55 | 47 | 68 | |||||