Chester State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chester State Park clear sky chart from 2005-11-06 to 2024-01-13.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
45%
24258
22%
74369
14%
24205
53%
24205
26%
46697

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
27%
759
24%
2459
9%
757
44%
757
21%
1496
January11th to 20thNight
29%
732
24%
2378
12%
732
44%
732
22%
1468
January21st to endNight
28%
792
27%
2574
14%
792
45%
792
24%
1555
February1st to 10thNight
30%
720
21%
2326
11%
720
43%
720
23%
1444
February11th to 20thNight
20%
702
22%
2098
7%
699
36%
699
22%
1363
February21st to endNight
25%
592
24%
1739
9%
592
40%
592
24%
1112
March1st to 10thNight
32%
720
26%
1980
13%
720
43%
720
30%
1230
March11th to 20thNight
28%
720
21%
1980
10%
720
39%
720
25%
1289
March21st to endNight
30%
792
21%
2178
7%
792
40%
792
24%
1451
April1st to 10thNight
35%
720
24%
1980
11%
720
46%
720
30%
1206
April11th to 20thNight
40%
711
25%
1803
10%
711
49%
711
35%
1116
April21st to endNight
43%
590
28%
1670
16%
590
51%
590
36%
980
May1st to 10thNight
47%
540
20%
1620
10%
540
54%
540
32%
948
May11th to 20thNight
46%
531
15%
1593
8%
531
50%
531
24%
1073
May21st to endNight
60%
582
18%
1744
14%
582
62%
582
28%
1117
June1st to 10thNight
57%
540
14%
1620
12%
540
58%
540
23%
1109
June11th to 20thNight
58%
540
14%
1620
11%
540
61%
540
25%
1105
June21st to endNight
62%
540
13%
1620
10%
540
64%
540
23%
1103
July1st to 10thNight
66%
525
10%
1575
9%
525
66%
525
22%
1105
July11th to 20thNight
68%
522
11%
1566
9%
522
68%
522
25%
1047
July21st to endNight
66%
591
13%
1672
10%
558
68%
558
23%
1159
August1st to 10thNight
62%
537
12%
1600
11%
534
62%
534
23%
1103
August11th to 20thNight
61%
534
16%
1598
13%
534
62%
534
22%
1095
August21st to endNight
60%
727
15%
1923
11%
727
62%
727
23%
1393
September1st to 10thNight
66%
720
19%
1980
16%
720
67%
720
31%
1275
September11th to 20thNight
57%
720
20%
1980
17%
720
59%
720
26%
1340
September21st to endNight
54%
720
20%
1980
16%
720
59%
720
26%
1326
October1st to 10thNight
55%
720
26%
2071
22%
720
61%
720
34%
1248
October11th to 20thNight
47%
720
29%
2160
24%
720
58%
720
32%
1267
October21st to endNight
51%
792
32%
2376
24%
792
62%
792
35%
1342
November1st to 10thNight
49%
740
29%
2221
23%
740
59%
740
35%
1262
November11th to 20thNight
43%
760
28%
2419
20%
760
55%
760
30%
1384
November21st to endNight
44%
760
28%
2470
20%
760
55%
760
29%
1435
December1st to 10thNight
35%
760
24%
2470
14%
760
48%
760
20%
1596
December11th to 20thNight
39%
759
28%
2919
20%
758
50%
758
24%
1647
December21st to endNight
32%
828
16%
4407
14%
817
43%
817
14%
2508

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
13%5%25%5%35%5%6%8%43%
74924
Night
14%6%25%5%3445%7%44%
74825
TransparencyDay
39%7%12%20%18%5%
74647
Night
38%6%11%19%20%6%
74621
SeeingDay
17%9%25%25%18%7%
14135
Night
17%9%23%30%19%3
24271

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
18%6%24424445%46%
1706
11th to 20thDay
17%7%35%5%24435%44%
1638
21st to endDay
16%6%26%43445%448%
1782
February1st to 10thDay
16%6%345%35%45%7%42%
1629
11th to 20thDay
21%5%14424445%46%
1748
21st to endDay
21%7%36%433346%41%
1516
March1st to 10thDay
15%6%2432334453%
1980
11th to 20thDay
17%6%26%5%246%5%7%41%
1980
21st to endDay
16%6%36%5%4445%6%41%
2178
April1st to 10thDay
12%324435%5%6%8%49%
1980
11th to 20thDay
13%6%245%345%5%8%47%
2106
21st to endDay
11%3244345%6%8%49%
2305
May1st to 10thDay
9%4245%36%5%6%9%47%
2340
11th to 20thDay
12%5%25%6%46%6%6%8%40%
2301
21st to endDay
11%6%36%5%45%5%7%8%40%
2531
June1st to 10thDay
9%5%26%6%46%6%7%12%37%
2340
11th to 20thDay
8%435%7%46%6%7%11%40%
2340
21st to endDay
6%425%7%5%7%7%8%10%40%
2340
July1st to 10thDay
9%5%37%7%47%7%8%10%32%
2340
11th to 20thDay
8%5%36%7%5%8%7%8%10%32%
2340
21st to endDay
7%5%37%7%5%8%7%8%11%33%
2547
August1st to 10thDay
12%6%27%6%47%7%9%10%31%
2327
11th to 20thDay
14%7%35%7%5%6%8%7%10%29%
2303
21st to endDay
11%6%36%7%46%7%7%10%33%
2409
September1st to 10thDay
9%425%5%46%6%7%9%42%
1980
11th to 20thDay
12%7%36%6%45%5%6%8%41%
1980
21st to endDay
16%7%35%5%445%46%42%
1980
October1st to 10thDay
15%5%24333345%53%
1886
11th to 20thDay
14%424323335%57%
1800
21st to endDay
14%5%24323335%57%
1980
November1st to 10thDay
14%5%23323336%56%
1857
11th to 20thDay
14%5%23324437%54%
1758
21st to endDay
16%42442345%6%50%
1710
December1st to 10thDay
19%7%344345%5%6%39%
1710
11th to 20thDay
18%424323346%51%
2153
21st to endDay
19%6%25%433446%43%
3124
January1st to 10thNight
19%5%25%434345%47%
2459
11th to 20thNight
18%6%25%42446%5%45%
2378
21st to endNight
17%7%25%323445%49%
2574
February1st to 10thNight
16%6%25%5%34445%46%
2326
11th to 20thNight
20%6%36%324446%43%
2098
21st to endNight
17%6%25%42445%8%42%
1739
March1st to 10thNight
16%6%25%423346%49%
1980
11th to 20thNight
15%5%35%6%345%5%7%42%
1980
21st to endNight
14%6%36%5%35%45%7%43%
2178
April1st to 10thNight
12%4244335%5%7%50%
1980
11th to 20thNight
12%43442445%6%52%
1803
21st to endNight
11%425%41345%8%52%
1670
May1st to 10thNight
8%4245%35%5%5%10%48%
1620
11th to 20thNight
11%7%36%5%35%6%7%9%37%
1592
21st to endNight
9%6%26%5%45%5%6%10%42%
1744
June1st to 10thNight
11%6%26%7%5%6%6%7%10%33%
1620
11th to 20thNight
10%6%26%7%35%5%8%11%37%
1620
21st to endNight
8%5%46%7%5%7%6%8%10%35%
1620
July1st to 10thNight
7%5%37%8%5%6%8%8%11%31%
1620
11th to 20thNight
8%5%28%6%46%7%9%12%34%
1620
21st to endNight
7%6%37%6%45%8%8%12%34%
1771
August1st to 10thNight
13%6%26%6%46%6%8%12%32%
1611
11th to 20thNight
11%6%36%6%46%7%7%11%34%
1598
21st to endNight
10%6%37%7%46%8%9%10%30%
1923
September1st to 10thNight
9%5%26%5%35%5%6%10%44%
1980
11th to 20thNight
13%6%37%6%3446%8%40%
1980
21st to endNight
15%6%26%6%3446%6%42%
1980
October1st to 10thNight
15%423433345%53%
2071
11th to 20thNight
14%6%25%423346%52%
2160
21st to endNight
12%5%23423335%57%
2376
November1st to 10thNight
13%5%24322346%55%
2221
11th to 20thNight
13%6%23424346%52%
2419
21st to endNight
14%5%2432445%7%49%
2470
December1st to 10thNight
19%7%35%434445%43%
2470
11th to 20thNight
18%5%24322335%52%
3042
21st to endNight
20%5%25%42445%6%42%
4532

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
41%48%18%23%6%
1707
11th to 20thDay
44%5%8%17%21%6%
1638
21st to endDay
39%35%21%23%8%
1782
February1st to 10thDay
42%410%21%18%5%
1629
11th to 20thDay
42%47%19%23%5%
1758
21st to endDay
46%39%15%19%8%
1516
March1st to 10thDay
36%37%20%24%10%
1980
11th to 20thDay
42%6%10%17%17%7%
1980
21st to endDay
44%6%10%18%19%3
2178
April1st to 10thDay
33%411%20%26%6%
1980
11th to 20thDay
36%6%10%20%19%10%
2106
21st to endDay
32%7%11%24%22%4
2305
May1st to 10thDay
33%8%14%21%19%4
2340
11th to 20thDay
40%9%15%19%16%2
2305
21st to endDay
39%9%13%23%15%2
2531
June1st to 10thDay
40%8%15%25%10%2
2340
11th to 20thDay
35%10%19%22%13%2
2340
21st to endDay
35%11%17%21%14%2
2340
July1st to 10thDay
42%12%17%16%10%3
2275
11th to 20thDay
41%12%21%18%7%1
2271
21st to endDay
40%11%20%20%8%1
2405
August1st to 10thDay
45%11%17%19%8%1
2314
11th to 20thDay
46%13%15%17%9%1
2303
21st to endDay
43%11%17%18%8%3
2409
September1st to 10thDay
36%9%15%19%17%4
1980
11th to 20thDay
41%8%11%16%21%3
1980
21st to endDay
44%6%8%20%16%6%
1980
October1st to 10thDay
35%5%7%21%26%6%
1886
11th to 20thDay
31%49%24%24%9%
1800
21st to endDay
32%36%20%29%10%
1980
November1st to 10thDay
33%47%18%30%9%
1857
11th to 20thDay
32%47%22%26%9%
1758
21st to endDay
35%5%8%20%22%9%
1710
December1st to 10thDay
45%5%7%21%17%5%
1710
11th to 20thDay
36%37%21%23%11%
2150
21st to endDay
42%5%7%21%21%3
3124
January1st to 10thNight
40%48%18%24%6%
2459
11th to 20thNight
41%49%17%24%6%
2378
21st to endNight
39%35%20%26%7%
2574
February1st to 10thNight
41%49%19%20%7%
2326
11th to 20thNight
44%48%16%23%6%
2099
21st to endNight
40%5%11%18%18%8%
1739
March1st to 10thNight
37%39%16%23%11%
1980
11th to 20thNight
40%5%11%16%21%7%
1980
21st to endNight
41%7%9%19%19%5%
2178
April1st to 10thNight
34%5%10%19%26%7%
1980
11th to 20thNight
33%49%23%22%10%
1803
21st to endNight
32%5%10%27%21%5%
1670
May1st to 10thNight
32%7%16%23%19%4
1620
11th to 20thNight
41%9%14%19%16%1
1593
21st to endNight
37%9%13%23%15%3
1745
June1st to 10thNight
43%9%16%20%11%1
1620
11th to 20thNight
39%12%16%20%11%2
1620
21st to endNight
41%11%16%17%12%3
1620
July1st to 10thNight
42%12%21%14%7%4
1575
11th to 20thNight
37%12%24%16%7%2
1566
21st to endNight
40%13%19%19%8%1
1672
August1st to 10thNight
42%11%22%18%6%1
1600
11th to 20thNight
41%12%20%16%10%1
1598
21st to endNight
43%12%16%18%8%2
1923
September1st to 10thNight
36%8%15%19%16%6%
1980
11th to 20thNight
41%9%12%18%18%2
1980
21st to endNight
42%6%11%17%17%6%
1980
October1st to 10thNight
34%5%9%19%27%6%
2071
11th to 20thNight
34%47%23%22%10%
2160
21st to endNight
31%46%20%28%12%
2376
November1st to 10thNight
32%47%17%27%13%
2221
11th to 20thNight
34%46%17%26%12%
2419
21st to endNight
35%46%20%27%7%
2470
December1st to 10thNight
44%5%8%18%20%6%
2470
11th to 20thNight
36%38%17%25%10%
3044
21st to endNight
42%48%21%22%3
4532

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
22%22%38%17%1
270
11th to 20thDay
26%20%33%16%5%
246
21st to endDay
25%19%42%11%3
264
February1st to 10thDay
23%21%38%12%5%
240
11th to 20thDay
37%15%39%8%1
240
21st to endDay
27%18%35%18%2
234
March1st to 10thDay
22%16%36%19%7%
420
11th to 20thDay
24%15%39%15%6%1
420
21st to endDay
24%16%35%18%6%1
462
April1st to 10thDay
22%13%33%20%10%2
420
11th to 20thDay
15%17%33%22%11%3
412
21st to endDay
16%10%30%24%14%5%
420
May1st to 10thDay
13%13%34%22%13%4
423
11th to 20thDay
16%7%21%30%18%9%
447
21st to endDay
16%5%16%28%21%14%
485
June1st to 10thDay
12%316%37%22%10%
450
11th to 20thDay
9%419%28%28%12%
450
21st to endDay
10%316%34%27%11%
450
July1st to 10thDay
10%110%27%35%18%
445
11th to 20thDay
9%210%30%32%16%
444
21st to endDay
6%212%36%32%12%
488
August1st to 10thDay
16%414%26%26%14%
446
11th to 20thDay
16%210%27%31%15%
439
21st to endDay
11%215%30%25%16%
495
September1st to 10thDay
10%212%30%34%12%
450
11th to 20thDay
15%414%28%28%12%
450
21st to endDay
19%5%18%29%23%5%
450
October1st to 10thDay
17%424%26%20%8%
450
11th to 20thDay
13%8%26%25%21%6%
450
21st to endDay
17%8%25%27%18%5%
495
November1st to 10thDay
21%7%24%26%18%4
455
11th to 20thDay
17%13%37%23%8%2
318
21st to endDay
13%11%36%26%12%2
270
December1st to 10thDay
26%13%37%19%5%
270
11th to 20thDay
24%12%35%20%7%3
270
21st to endDay
27%14%33%15%7%3
297
January1st to 10thNight
24%16%29%26%6%
760
11th to 20thNight
21%13%32%28%6%
732
21st to endNight
20%16%33%28%3
792
February1st to 10thNight
20%14%32%29%5%
720
11th to 20thNight
24%15%37%22%1
703
21st to endNight
20%16%34%26%4
592
March1st to 10thNight
20%11%34%29%6%
720
11th to 20thNight
19%13%35%24%8%
720
21st to endNight
18%14%33%28%7%
792
April1st to 10thNight
15%16%30%29%10%
720
11th to 20thNight
16%12%27%32%12%1
711
21st to endNight
14%7%31%33%16%
590
May1st to 10thNight
11%8%28%38%15%
540
11th to 20thNight
14%5%24%34%21%2
531
21st to endNight
12%314%34%34%3
584
June1st to 10thNight
13%314%39%27%4
540
11th to 20thNight
12%217%29%31%8%
540
21st to endNight
9%213%37%33%6%
540
July1st to 10thNight
10%38%34%37%8%
525
11th to 20thNight
11%25%32%41%10%
522
21st to endNight
9%310%31%40%7%
591
August1st to 10thNight
15%39%27%39%7%
537
11th to 20thNight
13%210%30%39%6%
534
21st to endNight
13%210%28%40%7%
727
September1st to 10thNight
11%310%30%41%6%
720
11th to 20thNight
15%312%29%36%5%
720
21st to endNight
18%5%13%32%27%4
720
October1st to 10thNight
17%418%28%27%6%
720
11th to 20thNight
17%8%22%28%21%3
720
21st to endNight
15%10%21%33%20%2
792
November1st to 10thNight
16%6%24%33%18%3
740
11th to 20thNight
15%12%26%34%12%1
760
21st to endNight
16%11%24%35%13%1
760
December1st to 10thNight
22%12%25%33%7%1
760
11th to 20thNight
20%9%25%33%12%1
760
21st to endNight
26%14%22%30%8%
836
Page generated at 2024-01-10 10:16:14. Version ac07

Copyright 2024 Attilla Danko


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