Purtis Creek State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Purtis Creek State Park clear sky chart from 2005-11-06 to 2024-01-22.

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
48%
23991
27%
74345
19%
23931
57%
23931
35%
41845

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
33%
949
29%
2458
10%
946
45%
946
36%
1500
January11th to 20thNight
32%
950
26%
2470
9%
950
43%
950
32%
1552
January21st to endNight
31%
1000
28%
2600
11%
1000
41%
1000
32%
1644
February1st to 10thNight
28%
857
24%
2297
8%
857
39%
857
30%
1453
February11th to 20thNight
25%
704
22%
2098
8%
700
36%
700
26%
1308
February21st to endNight
22%
507
27%
1691
9%
507
37%
507
22%
1032
March1st to 10thNight
28%
540
25%
1980
12%
540
42%
540
23%
1182
March11th to 20thNight
31%
540
24%
1980
14%
540
44%
540
24%
1178
March21st to endNight
31%
594
26%
2178
14%
594
47%
594
28%
1191
April1st to 10thNight
31%
540
25%
1980
14%
540
49%
540
30%
1059
April11th to 20thNight
32%
533
24%
1816
14%
533
47%
533
28%
1041
April21st to endNight
35%
540
27%
1771
17%
540
51%
540
33%
978
May1st to 10thNight
35%
540
24%
1620
17%
540
47%
540
32%
955
May11th to 20thNight
47%
531
22%
1594
19%
531
54%
531
34%
934
May21st to endNight
54%
584
25%
1745
20%
582
64%
582
36%
1021
June1st to 10thNight
72%
540
23%
1620
24%
540
76%
540
44%
860
June11th to 20thNight
73%
540
26%
1620
28%
540
77%
540
51%
803
June21st to endNight
76%
540
26%
1620
29%
540
79%
540
45%
857
July1st to 10thNight
77%
525
23%
1575
26%
525
80%
525
40%
874
July11th to 20thNight
86%
522
29%
1566
35%
522
89%
522
61%
712
July21st to endNight
83%
591
26%
1673
29%
558
86%
558
50%
844
August1st to 10thNight
88%
537
33%
1601
38%
534
89%
534
62%
717
August11th to 20thNight
77%
534
29%
1600
31%
534
78%
534
40%
882
August21st to endNight
82%
594
25%
2013
29%
594
83%
594
41%
1026
September1st to 10thNight
74%
540
24%
1980
29%
540
75%
540
36%
1013
September11th to 20thNight
71%
540
25%
1980
29%
540
73%
540
34%
1034
September21st to endNight
73%
540
34%
1980
35%
540
77%
540
43%
921
October1st to 10thNight
71%
612
35%
2052
32%
612
76%
612
47%
961
October11th to 20thNight
55%
720
35%
2160
19%
720
65%
720
43%
1163
October21st to endNight
46%
792
33%
2376
20%
792
55%
792
37%
1315
November1st to 10thNight
52%
740
31%
2220
20%
740
59%
740
40%
1223
November11th to 20thNight
47%
786
31%
2306
18%
786
56%
786
38%
1299
November21st to endNight
37%
950
27%
2470
13%
950
45%
950
32%
1572
December1st to 10thNight
37%
950
30%
2470
13%
950
48%
950
35%
1526
December11th to 20thNight
33%
949
28%
2864
13%
948
41%
948
26%
1814
December21st to endNight
33%
1040
17%
4321
12%
1026
42%
1026
22%
2401

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
12%5%25%43445%7%48%
75030
Night
11%5%2442345%7%54%
74935
TransparencyDay
35%6%11%22%20%7%
74755
Night
30%5%11%21%22%10%
74730
SeeingDay
12%7%21%27%24%8%
13993
Night
13%7%27%34%17%2
23998

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
14%6%25%423346%51%
1707
11th to 20thDay
15%5%35%43435%6%48%
1710
21st to endDay
18%7%24313246%50%
1791
February1st to 10thDay
21%7%46%434345%41%
1678
11th to 20thDay
21%8%35%42433442%
1749
21st to endDay
22%7%3332334446%
1563
March1st to 10thDay
19%7%35%5%24347%42%
1980
11th to 20thDay
18%7%35%424446%42%
1980
21st to endDay
14%8%35%5%24445%46%
2178
April1st to 10thDay
13%7%25%4345%5%7%44%
1980
11th to 20thDay
15%5%36%5%345%6%7%42%
2090
21st to endDay
13%5%24435%46%6%46%
2185
May1st to 10thDay
13%6%35%5%4445%7%43%
2340
11th to 20thDay
12%7%26%6%35%5%6%8%42%
2302
21st to endDay
10%6%36%6%45%7%7%8%37%
2531
June1st to 10thDay
7%4235%26%5%7%11%49%
2340
11th to 20thDay
5%3145%35%7%8%9%50%
2340
21st to endDay
44245%46%5%7%10%51%
2340
July1st to 10thDay
7%5%35%6%47%7%8%11%38%
2340
11th to 20thDay
3213436%6%6%9%56%
2340
21st to endDay
43245%36%7%8%11%47%
2546
August1st to 10thDay
421233445%11%61%
2328
11th to 20thDay
7%425%4345%7%12%49%
2301
21st to endDay
5%4145%35%7%7%10%47%
2337
September1st to 10thDay
10%425%5%345%5%8%50%
1980
11th to 20thDay
9%5%25%5%46%6%7%7%45%
1980
21st to endDay
7%42442446%7%56%
1980
October1st to 10thDay
6%32343445%6%60%
1889
11th to 20thDay
13%423423345%58%
1800
21st to endDay
15%42432332359%
1980
November1st to 10thDay
12%5%25%324436%55%
1858
11th to 20thDay
9%5%24423346%56%
1871
21st to endDay
19%6%25%423345%48%
1710
December1st to 10thDay
16%6%24424446%48%
1710
11th to 20thDay
16%7%25%434445%44%
2161
21st to endDay
17%8%25%5%23346%44%
3135
January1st to 10thNight
14%5%2432335%6%53%
2458
11th to 20thNight
16%6%34323346%51%
2470
21st to endNight
15%7%24423335%51%
2600
February1st to 10thNight
17%5%35%423345%50%
2297
11th to 20thNight
19%6%34423345%47%
2098
21st to endNight
19%6%34423345%47%
1691
March1st to 10thNight
17%6%25%5%2345%7%44%
1980
11th to 20thNight
13%7%34434337%48%
1980
21st to endNight
14%5%2442345%7%52%
2178
April1st to 10thNight
10%4243345%5%8%52%
1980
11th to 20thNight
12%6%2443445%7%49%
1816
21st to endNight
11%42433445%7%53%
1771
May1st to 10thNight
9%5%345%3445%8%49%
1620
11th to 20thNight
10%325%42446%10%50%
1593
21st to endNight
8%4234345%7%9%51%
1745
June1st to 10thNight
5%21342445%12%57%
1620
11th to 20thNight
4213323449%66%
1620
21st to endNight
5%2233245%6%9%60%
1620
July1st to 10thNight
43244246%7%11%52%
1620
11th to 20thNight
221222236%10%68%
1620
21st to endNight
2213425%5%7%12%58%
1772
August1st to 10thNight
221221335%10%69%
1611
11th to 20thNight
7%32443337%10%53%
1600
21st to endNight
33145%346%6%11%55%
2013
September1st to 10thNight
7%424424447%56%
1980
11th to 20thNight
10%324434347%56%
1980
21st to endNight
6%314423448%62%
1980
October1st to 10thNight
5%31332345%8%64%
2052
11th to 20thNight
12%313313345%61%
2160
21st to endNight
15%41322233361%
2376
November1st to 10thNight
11%5%23323345%60%
2220
11th to 20thNight
8%5%25%32335%6%57%
2306
21st to endNight
16%6%23433346%50%
2470
December1st to 10thNight
14%5%24423346%52%
2470
11th to 20thNight
14%7%35%423345%48%
3036
21st to endNight
16%6%2442333452%
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
37%37%19%27%7%
1708
11th to 20thDay
38%38%21%23%6%
1710
21st to endDay
39%35%17%26%10%
1791
February1st to 10thDay
47%45%16%19%9%
1678
11th to 20thDay
47%36%16%19%8%
1759
21st to endDay
43%46%13%21%13%
1563
March1st to 10thDay
44%48%15%21%10%
1980
11th to 20thDay
43%5%8%16%21%6%
1980
21st to endDay
41%5%9%17%22%6%
2178
April1st to 10thDay
40%5%10%21%16%8%
1980
11th to 20thDay
40%6%10%16%20%8%
2090
21st to endDay
38%5%9%21%22%4
2185
May1st to 10thDay
40%7%8%21%18%6%
2340
11th to 20thDay
40%7%12%22%17%1
2306
21st to endDay
42%8%14%20%16%1
2531
June1st to 10thDay
28%9%17%30%14%2
2340
11th to 20thDay
28%9%16%28%16%4
2340
21st to endDay
27%9%14%28%19%2
2340
July1st to 10thDay
37%10%20%23%10%1
2276
11th to 20thDay
22%7%18%33%18%3
2271
21st to endDay
26%12%17%33%11%1
2405
August1st to 10thDay
18%7%17%36%20%2
2314
11th to 20thDay
28%8%17%28%17%2
2301
21st to endDay
30%10%15%28%15%2
2337
September1st to 10thDay
33%6%12%22%19%9%
1980
11th to 20thDay
36%9%12%17%18%8%
1980
21st to endDay
27%5%10%21%24%13%
1980
October1st to 10thDay
24%5%13%21%21%16%
1889
11th to 20thDay
30%46%18%27%16%
1800
21st to endDay
32%45%17%26%15%
1980
November1st to 10thDay
32%5%8%22%25%9%
1858
11th to 20thDay
30%39%18%28%11%
1871
21st to endDay
42%35%18%23%9%
1710
December1st to 10thDay
37%5%10%19%21%8%
1710
11th to 20thDay
41%48%15%23%9%
2159
21st to endDay
42%36%22%21%7%
3135
January1st to 10thNight
34%36%18%26%12%
2458
11th to 20thNight
36%38%19%24%10%
2470
21st to endNight
38%25%15%26%13%
2600
February1st to 10thNight
38%38%17%21%14%
2297
11th to 20thNight
41%46%16%23%10%
2098
21st to endNight
41%48%13%18%16%
1691
March1st to 10thNight
41%48%14%20%13%
1980
11th to 20thNight
38%6%8%14%25%8%
1980
21st to endNight
32%5%11%19%25%8%
2178
April1st to 10thNight
31%411%21%19%13%
1980
11th to 20thNight
34%6%11%17%19%14%
1816
21st to endNight
31%410%21%27%6%
1771
May1st to 10thNight
34%5%12%21%19%8%
1620
11th to 20thNight
31%7%15%27%18%3
1594
21st to endNight
28%9%17%26%18%2
1746
June1st to 10thNight
22%7%16%31%20%4
1620
11th to 20thNight
17%7%15%35%21%5%
1620
21st to endNight
21%8%14%26%26%5%
1620
July1st to 10thNight
23%10%19%33%13%2
1575
11th to 20thNight
12%6%21%35%23%3
1566
21st to endNight
16%9%24%35%15%1
1673
August1st to 10thNight
12%418%37%24%4
1601
11th to 20thNight
25%8%16%27%19%6%
1600
21st to endNight
22%8%17%31%17%4
2013
September1st to 10thNight
27%6%14%23%20%11%
1980
11th to 20thNight
29%5%14%22%20%10%
1980
21st to endNight
22%411%20%28%15%
1980
October1st to 10thNight
19%5%10%26%20%19%
2052
11th to 20thNight
27%37%17%25%21%
2160
21st to endNight
30%35%16%26%20%
2376
November1st to 10thNight
28%48%20%27%13%
2220
11th to 20thNight
30%48%19%26%14%
2306
21st to endNight
37%38%16%24%11%
2470
December1st to 10thNight
34%5%10%20%22%11%
2470
11th to 20thNight
40%36%15%24%12%
3037
21st to endNight
36%37%17%26%11%
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
21%14%35%25%5%
270
11th to 20thDay
19%17%40%17%6%1
270
21st to endDay
25%13%39%18%6%
267
February1st to 10thDay
28%15%33%19%5%
240
11th to 20thDay
29%20%34%15%2
240
21st to endDay
31%19%35%15%1
198
March1st to 10thDay
25%16%37%19%3
240
11th to 20thDay
21%20%35%18%5%1
240
21st to endDay
17%17%42%18%5%
264
April1st to 10thDay
21%13%38%23%5%
240
11th to 20thDay
19%11%35%26%9%
368
21st to endDay
17%11%36%26%8%2
445
May1st to 10thDay
14%10%34%32%8%1
603
11th to 20thDay
16%6%25%32%18%3
625
21st to endDay
12%5%24%34%20%4
679
June1st to 10thDay
7%312%38%32%10%
630
11th to 20thDay
6%116%39%30%7%
630
21st to endDay
4114%32%35%13%
630
July1st to 10thDay
6%28%34%35%15%
621
11th to 20thDay
21432%45%16%
618
21st to endDay
36%26%46%18%
684
August1st to 10thDay
315%29%47%15%
626
11th to 20thDay
7%15%27%47%12%
615
21st to endDay
7%1419%42%27%
456
September1st to 10thDay
7%5%17%48%23%
270
11th to 20thDay
318%25%40%23%
270
21st to endDay
10%26%29%33%19%
270
October1st to 10thDay
4317%30%39%7%
270
11th to 20thDay
10%9%27%26%21%6%
270
21st to endDay
25%11%22%25%13%4
297
November1st to 10thDay
17%431%31%13%4
270
11th to 20thDay
14%10%29%32%13%1
270
21st to endDay
23%15%28%22%11%1
270
December1st to 10thDay
17%13%32%25%10%3
270
11th to 20thDay
23%15%36%20%6%
270
21st to endDay
21%14%37%21%7%1
297
January1st to 10thNight
17%10%36%30%7%
950
11th to 20thNight
21%13%30%30%6%
950
21st to endNight
18%12%36%29%5%
1000
February1st to 10thNight
20%12%36%27%5%
857
11th to 20thNight
24%12%37%25%2
704
21st to endNight
23%15%38%21%3
507
March1st to 10thNight
19%12%38%24%7%
540
11th to 20thNight
16%11%38%29%6%
540
21st to endNight
15%12%41%27%5%1
594
April1st to 10thNight
12%9%44%29%6%
540
11th to 20thNight
14%12%39%25%10%1
533
21st to endNight
13%8%42%28%8%1
540
May1st to 10thNight
11%8%41%30%9%1
540
11th to 20thNight
10%5%33%35%17%1
531
21st to endNight
8%429%38%19%2
584
June1st to 10thNight
6%115%43%31%4
540
11th to 20thNight
4216%53%24%2
540
21st to endNight
4212%39%37%6%
540
July1st to 10thNight
49%46%34%7%
525
11th to 20thNight
26%44%41%7%
522
21st to endNight
216%43%43%6%
591
August1st to 10thNight
3447%42%4
537
11th to 20thNight
8%6%40%39%7%
534
21st to endNight
5%437%48%6%
594
September1st to 10thNight
7%19%34%41%6%
540
11th to 20thNight
10%19%36%40%4
540
21st to endNight
6%112%38%38%3
540
October1st to 10thNight
6%117%48%23%5%
612
11th to 20thNight
13%5%24%39%17%2
720
21st to endNight
18%7%28%29%17%2
792
November1st to 10thNight
12%429%38%15%2
740
11th to 20thNight
9%10%30%38%12%
786
21st to endNight
20%11%29%27%12%1
950
December1st to 10thNight
17%10%33%33%7%
950
11th to 20thNight
21%10%31%33%5%
950
21st to endNight
21%10%33%31%6%
1045
Page generated at 2024-01-19 08:28:30. Version ac07

Copyright 2024 Attilla Danko


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