Croft State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Croft State Park clear sky chart from 2005-11-05 to 2019-06-02.

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
47%
18002
22%
53814
14%
17963
55%
17963
27%
34194

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 15thNight
30%
838
24%
2717
11%
836
46%
836
22%
1654
January16th to endNight
29%
896
25%
2912
14%
896
45%
896
25%
1744
February1st to 15thNight
30%
821
24%
2570
12%
820
44%
820
26%
1574
February16th to endNight
25%
735
24%
2205
9%
735
41%
735
24%
1415
March1st to 15thNight
33%
840
26%
2310
14%
840
43%
840
28%
1466
March16th to endNight
35%
896
20%
2464
10%
896
43%
896
27%
1605
April1st to 15thNight
39%
838
23%
2282
12%
838
47%
838
31%
1423
April16th to endNight
43%
682
25%
1928
13%
682
52%
682
32%
1179
May1st to 15thNight
49%
630
18%
1890
10%
630
55%
630
26%
1213
May16th to endNight
58%
657
16%
1971
12%
657
60%
657
25%
1299
June1st to 15thNight
63%
588
14%
1765
13%
588
64%
588
26%
1180
June16th to endNight
68%
585
14%
1755
12%
585
69%
585
26%
1167
July1st to 15thNight
65%
555
10%
1665
10%
555
65%
555
22%
1161
July16th to endNight
67%
612
12%
1739
9%
579
68%
579
24%
1201
August1st to 15thNight
66%
575
13%
1715
12%
572
67%
572
22%
1222
August16th to endNight
66%
689
15%
1980
13%
689
67%
689
23%
1390
September1st to 15thNight
64%
780
18%
2145
15%
780
66%
780
28%
1428
September16th to endNight
56%
777
20%
2145
16%
777
60%
777
27%
1451
October1st to 15thNight
54%
780
28%
2254
24%
780
60%
780
31%
1388
October16th to endNight
52%
832
34%
2496
25%
832
66%
832
39%
1359
November1st to 15thNight
52%
820
28%
2534
22%
820
61%
820
32%
1473
November16th to endNight
46%
840
26%
2730
20%
840
56%
840
29%
1572
December1st to 15thNight
39%
840
24%
2730
15%
840
51%
840
23%
1728
December16th to endNight
35%
896
22%
2912
14%
896
45%
896
21%
1902

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%244345%5%7%43%
54515
Night
13%5%2443445%7%44%
54012
TransparencyDay
38%6%12%20%17%4
54216
Night
38%6%11%18%19%5%
53815
SeeingDay
16%7%20%23%20%11%
7798
Night
16%7%22%29%21%3
18009

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 15thDay
17%7%34323445%44%
1881
16th to endDay
17%5%24322345%49%
2016
February1st to 15thDay
16%5%23423446%45%
1949
16th to endDay
19%5%24423336%44%
1840
March1st to 15thDay
17%423423445%47%
2308
16th to endDay
16%5%2442445%7%43%
2463
April1st to 15thDay
12%4234245%5%8%46%
2326
16th to endDay
13%42442445%6%47%
2648
May1st to 15thDay
11%4345%35%6%5%7%42%
2721
16th to endDay
11%415%5%345%6%8%41%
2847
June1st to 15thDay
8%4246%36%5%7%11%38%
2548
16th to endDay
5%325%6%46%7%8%9%42%
2535
July1st to 15thDay
8%6%26%6%46%6%7%9%33%
2535
16th to endDay
7%5%25%6%46%7%9%11%32%
2673
August1st to 15thDay
13%6%26%5%45%7%7%10%29%
2487
16th to endDay
10%5%26%5%46%6%6%10%34%
2557
September1st to 15thDay
10%425%5%446%6%8%41%
2145
16th to endDay
16%6%245%34446%40%
2145
October1st to 15thDay
15%413312235%55%
2035
16th to endDay
12%31331322460%
2080
November1st to 15thDay
15%413323336%51%
1980
16th to endDay
15%42342434451%
1890
December1st to 15thDay
17%7%34324445%42%
1890
16th to endDay
22%6%24423335%40%
2016
January1st to 15thNight
17%42442434447%
2717
16th to endNight
16%5%14313335%49%
2912
February1st to 15thNight
16%423433345%49%
2561
16th to endNight
17%6%24423445%43%
2205
March1st to 15thNight
15%5%25%323346%46%
2310
16th to endNight
14%425%5%24446%44%
2464
April1st to 15thNight
13%5%13423447%47%
2282
16th to endNight
10%5%24424436%50%
1928
May1st to 15thNight
10%5%35%5%345%5%8%41%
1889
16th to endNight
12%415%5%35%5%7%9%38%
1970
June1st to 15thNight
11%425%5%47%5%9%9%34%
1765
16th to endNight
5%5%246%46%7%7%9%39%
1755
July1st to 15thNight
7%5%26%7%47%8%8%11%30%
1755
16th to endNight
6%436%6%36%7%10%13%30%
1847
August1st to 15thNight
12%6%35%5%35%7%8%11%30%
1726
16th to endNight
10%5%25%6%5%6%6%7%10%33%
1980
September1st to 15thNight
11%5%25%4345%6%9%39%
2145
16th to endNight
15%6%24434446%42%
2145
October1st to 15thNight
15%413423335%50%
2254
16th to endNight
11%313323335%59%
2496
November1st to 15thNight
15%413223336%53%
2534
16th to endNight
13%323423346%50%
2730
December1st to 15thNight
17%6%14424436%43%
2730
16th to endNight
21%5%24424446%40%
2912

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 15thDay
42%5%6%18%21%5%
1882
16th to endDay
38%27%20%22%8%
2016
February1st to 15thDay
39%48%20%22%4
1951
16th to endDay
42%47%21%19%4
1840
March1st to 15thDay
39%46%21%20%7%
2308
16th to endDay
39%6%12%20%18%3
2464
April1st to 15thDay
34%5%10%21%21%5%
2326
16th to endDay
36%5%10%20%19%7%
2648
May1st to 15thDay
38%7%14%19%16%2
2721
16th to endDay
38%7%15%21%14%1
2851
June1st to 15thDay
37%9%18%23%10%
2548
16th to endDay
33%11%17%21%13%1
2535
July1st to 15thDay
41%10%18%16%9%3
2396
16th to endDay
38%11%19%19%9%1
2518
August1st to 15thDay
46%10%15%17%10%
2474
16th to endDay
42%11%17%17%9%2
2557
September1st to 15thDay
38%8%14%17%17%3
2145
16th to endDay
43%5%10%18%16%4
2145
October1st to 15thDay
32%411%21%24%5%
2035
16th to endDay
29%25%22%28%10%
2080
November1st to 15thDay
33%48%18%26%8%
1980
16th to endDay
36%37%20%24%7%
1890
December1st to 15thDay
44%48%19%18%5%
1890
16th to endDay
47%48%19%16%4
2016
January1st to 15thNight
39%48%16%24%6%
2717
16th to endNight
38%36%20%24%7%
2912
February1st to 15thNight
38%48%20%22%5%
2570
16th to endNight
41%49%19%20%4
2205
March1st to 15thNight
38%49%17%20%9%
2310
16th to endNight
39%5%10%17%22%4
2464
April1st to 15thNight
35%410%21%22%6%
2282
16th to endNight
35%49%20%21%8%
1928
May1st to 15thNight
38%7%12%20%17%2
1890
16th to endNight
38%10%12%22%13%2
1972
June1st to 15thNight
40%9%18%21%9%1
1765
16th to endNight
37%10%16%19%11%3
1755
July1st to 15thNight
41%12%19%15%7%2
1665
16th to endNight
37%14%21%16%7%2
1739
August1st to 15thNight
43%11%18%15%9%
1715
16th to endNight
42%10%18%16%10%
1980
September1st to 15thNight
38%9%16%17%14%3
2145
16th to endNight
41%6%12%17%17%4
2145
October1st to 15thNight
35%5%9%20%22%6%
2254
16th to endNight
28%26%21%28%11%
2496
November1st to 15thNight
33%36%17%26%10%
2534
16th to endNight
34%47%17%26%8%
2730
December1st to 15thNight
41%48%19%18%6%
2730
16th to endNight
44%410%16%18%5%
2912

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 15thDay
23%17%30%22%5%
180
16th to endDay
17%21%38%15%7%
192
February1st to 15thDay
21%20%40%12%4
180
16th to endDay
27%16%33%16%5%
159
March1st to 15thDay
21%13%34%23%5%
388
16th to endDay
15%14%35%22%9%1
416
April1st to 15thDay
16%12%30%22%14%2
390
16th to endDay
16%6%26%24%19%6%
379
May1st to 15thDay
13%8%25%22%22%8%
408
16th to endDay
15%315%23%26%15%
459
June1st to 15thDay
10%211%26%29%20%
379
16th to endDay
8%114%26%23%26%
375
July1st to 15thDay
9%19%22%34%23%
365
16th to endDay
10%15%30%32%20%
390
August1st to 15thDay
21%28%18%28%21%
358
16th to endDay
12%18%24%26%25%
396
September1st to 15thDay
13%212%18%30%21%
375
16th to endDay
22%115%21%26%12%
374
October1st to 15thDay
18%417%27%21%10%
375
16th to endDay
14%7%18%29%24%6%
400
November1st to 15thDay
26%6%21%23%17%4
308
16th to endDay
10%11%30%27%17%3
180
December1st to 15thDay
31%10%30%19%8%
180
16th to endDay
31%11%33%17%5%
192
January1st to 15thNight
20%15%28%28%7%
840
16th to endNight
19%13%33%29%3
896
February1st to 15thNight
20%11%33%29%4
824
16th to endNight
20%14%36%25%3
735
March1st to 15thNight
18%10%33%30%6%
840
16th to endNight
18%9%31%29%10%
896
April1st to 15thNight
16%11%29%28%13%
838
16th to endNight
14%7%28%30%18%
682
May1st to 15thNight
12%5%24%35%20%1
630
16th to endNight
14%114%27%35%5%
659
June1st to 15thNight
12%110%34%30%9%
588
16th to endNight
7%110%31%38%10%
585
July1st to 15thNight
9%18%30%40%8%
555
16th to endNight
8%18%26%44%9%
612
August1st to 15thNight
16%426%41%9%
575
16th to endNight
12%17%26%43%8%
689
September1st to 15thNight
12%110%27%39%7%
780
16th to endNight
19%114%26%32%4
777
October1st to 15thNight
17%417%25%28%6%
780
16th to endNight
13%6%23%30%23%2
832
November1st to 15thNight
17%5%20%36%17%2
820
16th to endNight
15%9%24%32%17%
840
December1st to 15thNight
22%9%22%32%11%
840
16th to endNight
22%9%26%32%8%
896
Page generated at 2019-06-02 19:43:06. Version ac04

Copyright 2019 A. Danko


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