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Flint Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Flint Ridge Observatory clear sky chart from 2005-11-06 to 2024-01-17.

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
39%
23483
20%
74770
12%
23436
49%
23436
24%
47359

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
21%
757
22%
2533
7%
757
39%
757
20%
1582
January11th to 20thNight
25%
748
21%
2430
9%
748
39%
748
19%
1599
January21st to endNight
20%
792
21%
2574
7%
792
38%
792
21%
1622
February1st to 10thNight
24%
720
18%
2340
8%
720
38%
720
19%
1521
February11th to 20thNight
17%
701
16%
2275
4%
700
33%
700
17%
1481
February21st to endNight
17%
592
22%
1753
7%
592
34%
592
19%
1197
March1st to 10thNight
23%
720
23%
1980
8%
720
38%
720
26%
1245
March11th to 20thNight
26%
720
22%
1980
9%
720
37%
720
22%
1308
March21st to endNight
23%
792
19%
2178
7%
792
34%
792
24%
1459
April1st to 10thNight
26%
720
17%
1811
5%
720
34%
720
24%
1262
April11th to 20thNight
35%
711
19%
1775
7%
711
40%
711
29%
1178
April21st to endNight
36%
694
20%
1774
7%
694
43%
694
28%
1190
May1st to 10thNight
40%
540
17%
1620
10%
540
45%
540
23%
1086
May11th to 20thNight
40%
491
15%
1552
10%
491
45%
491
21%
1049
May21st to endNight
55%
388
17%
1551
18%
388
60%
388
22%
920
June1st to 10thNight
56%
360
20%
1440
20%
360
64%
360
25%
827
June11th to 20thNight
58%
360
17%
1440
20%
360
61%
360
22%
886
June21st to endNight
61%
360
19%
1440
20%
360
69%
360
27%
810
July1st to 10thNight
60%
350
15%
1400
18%
350
63%
350
21%
858
July11th to 20thNight
69%
497
16%
1541
13%
497
72%
497
31%
935
July21st to endNight
69%
591
16%
1672
13%
558
72%
558
31%
1036
August1st to 10thNight
66%
537
17%
1600
13%
534
68%
534
28%
1054
August11th to 20thNight
65%
552
19%
1616
14%
552
66%
552
29%
1058
August21st to endNight
62%
792
20%
1980
12%
792
64%
792
32%
1328
September1st to 10thNight
58%
720
21%
1800
13%
720
60%
720
31%
1225
September11th to 20thNight
57%
720
29%
1839
20%
720
61%
720
37%
1148
September21st to endNight
48%
720
20%
2057
15%
720
54%
720
27%
1354
October1st to 10thNight
48%
720
20%
2160
18%
720
53%
720
28%
1357
October11th to 20thNight
46%
720
25%
2160
19%
720
56%
720
31%
1290
October21st to endNight
38%
792
27%
2376
16%
792
52%
792
30%
1430
November1st to 10thNight
41%
740
27%
2249
18%
740
53%
740
33%
1291
November11th to 20thNight
34%
760
24%
2565
14%
760
48%
760
24%
1501
November21st to endNight
34%
760
22%
2660
14%
760
48%
760
22%
1602
December1st to 10thNight
25%
760
19%
2660
7%
760
40%
760
18%
1715
December11th to 20thNight
28%
760
19%
3179
10%
759
42%
759
18%
1950
December21st to endNight
31%
826
13%
4810
11%
817
44%
817
11%
3005

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
14%6%35%5%35%5%6%8%41%
74680
Night
14%6%25%5%35%5%6%7%43%
75149
TransparencyDay
40%8%13%22%15%3
74394
Night
39%7%13%23%16%3
74954
SeeingDay
18%12%24%24%16%6%
13784
Night
17%10%28%31%13%1
23499

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
12%7%36%446%5%5%6%42%
1630
11th to 20thDay
15%6%36%6%35%5%5%7%38%
1674
21st to endDay
14%8%47%6%345%5%6%39%
1782
February1st to 10thDay
13%10%37%7%45%45%6%37%
1620
11th to 20thDay
16%7%36%6%35%5%46%39%
1573
21st to endDay
16%8%36%5%345%46%40%
1497
March1st to 10thDay
13%6%246%2445%7%48%
1980
11th to 20thDay
15%7%26%5%35%5%6%7%39%
1980
21st to endDay
15%7%37%5%35%5%5%6%38%
2178
April1st to 10thDay
11%6%35%5%36%5%7%9%40%
2148
11th to 20thDay
13%5%35%5%35%448%45%
2134
21st to endDay
18%6%35%5%35%5%5%6%39%
2200
May1st to 10thDay
17%5%26%6%346%6%8%36%
2340
11th to 20thDay
21%5%25%5%35%5%6%7%35%
2340
21st to endDay
15%5%25%6%35%5%6%8%39%
2725
June1st to 10thDay
12%435%435%5%6%10%42%
2520
11th to 20thDay
10%5%35%5%46%6%8%10%37%
2520
21st to endDay
10%3245%36%7%6%10%44%
2520
July1st to 10thDay
8%5%36%6%36%5%7%8%41%
2520
11th to 20thDay
6%425%6%45%7%8%10%43%
2362
21st to endDay
9%6%26%6%46%6%8%10%37%
2547
August1st to 10thDay
10%5%26%6%5%7%8%7%9%36%
2327
11th to 20thDay
11%5%26%6%46%6%7%10%39%
2267
21st to endDay
10%5%25%6%35%6%6%9%43%
2376
September1st to 10thDay
15%6%25%5%3445%7%44%
2160
11th to 20thDay
13%5%34435%5%6%7%46%
2118
21st to endDay
19%6%25%5%3446%7%40%
1901
October1st to 10thDay
16%5%25%5%3336%7%46%
1800
11th to 20thDay
16%5%244345%5%6%46%
1800
21st to endDay
15%5%3443345%6%48%
1980
November1st to 10thDay
11%434434447%52%
1828
11th to 20thDay
15%6%25%43445%6%46%
1611
21st to endDay
15%5%245%35%448%45%
1520
December1st to 10thDay
16%8%45%435%6%7%7%35%
1520
11th to 20thDay
16%435%5%45%5%5%7%40%
1910
21st to endDay
17%5%25%6%37%7%6%9%31%
2772
January1st to 10thNight
12%7%345%35%6%5%8%42%
2533
11th to 20thNight
16%7%36%5%345%6%6%38%
2430
21st to endNight
14%7%35%5%35%45%7%42%
2574
February1st to 10thNight
14%8%36%43446%7%40%
2340
11th to 20thNight
15%8%35%5%35%6%6%5%39%
2273
21st to endNight
15%9%45%6%345%5%7%38%
1753
March1st to 10thNight
11%5%25%5%35%5%5%5%49%
1980
11th to 20thNight
16%6%25%434446%44%
1980
21st to endNight
15%6%36%5%3445%6%43%
2178
April1st to 10thNight
15%7%36%7%35%5%5%7%39%
1811
11th to 20thNight
13%426%6%345%7%8%43%
1775
21st to endNight
17%5%24435%5%5%7%43%
1774
May1st to 10thNight
17%5%25%6%45%46%8%39%
1620
11th to 20thNight
17%6%36%5%36%5%5%5%40%
1552
21st to endNight
13%425%5%35%6%7%9%41%
1550
June1st to 10thNight
10%4145%346%7%9%47%
1440
11th to 20thNight
12%6%145%35%5%7%9%42%
1440
21st to endNight
9%324435%6%8%11%43%
1440
July1st to 10thNight
10%436%6%45%5%6%10%41%
1440
11th to 20thNight
6%435%6%36%5%7%10%47%
1593
21st to endNight
8%424446%6%10%11%41%
1771
August1st to 10thNight
8%6%25%6%36%7%7%7%42%
1611
11th to 20thNight
10%6%26%5%45%5%6%9%42%
1616
21st to endNight
11%5%246%35%5%6%9%43%
1980
September1st to 10thNight
16%5%26%4345%6%6%45%
1800
11th to 20thNight
12%6%25%5%24346%51%
1839
21st to endNight
18%5%25%5%345%37%44%
2057
October1st to 10thNight
19%5%1442345%6%46%
2160
11th to 20thNight
14%5%2442445%6%51%
2160
21st to endNight
15%5%243345%46%50%
2376
November1st to 10thNight
10%6%25%43345%6%53%
2249
11th to 20thNight
14%7%3442445%6%47%
2565
21st to endNight
13%425%5%35%5%5%8%44%
2660
December1st to 10thNight
15%7%36%5%345%5%7%40%
2660
11th to 20thNight
16%6%35%6%35%5%5%7%41%
3285
21st to endNight
16%5%36%6%46%7%7%9%33%
4884

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
42%6%10%23%16%2
1631
11th to 20thDay
45%6%14%21%13%1
1674
21st to endDay
45%5%13%21%13%3
1782
February1st to 10thDay
47%7%13%20%10%3
1620
11th to 20thDay
45%6%11%22%14%2
1582
21st to endDay
45%6%11%20%14%4
1497
March1st to 10thDay
37%5%13%24%19%2
1980
11th to 20thDay
43%5%11%19%17%5%
1980
21st to endDay
46%6%11%18%15%3
2178
April1st to 10thDay
40%7%14%18%18%4
2148
11th to 20thDay
39%5%11%20%19%5%
2134
21st to endDay
44%7%9%21%14%4
2200
May1st to 10thDay
43%8%14%19%14%2
2340
11th to 20thDay
46%9%11%19%12%3
2344
21st to endDay
40%9%14%24%11%1
2725
June1st to 10thDay
36%9%13%25%16%1
2520
11th to 20thDay
39%11%15%20%13%2
2520
21st to endDay
32%11%16%25%14%2
2520
July1st to 10thDay
37%10%13%22%15%3
2450
11th to 20thDay
32%10%15%26%15%2
2291
21st to endDay
38%11%13%20%17%2
2405
August1st to 10thDay
40%11%14%23%11%1
2314
11th to 20thDay
39%9%16%21%14%1
2267
21st to endDay
36%10%15%23%13%3
2376
September1st to 10thDay
40%8%11%19%19%4
2160
11th to 20thDay
35%7%10%25%20%3
2118
21st to endDay
44%6%11%19%18%2
1901
October1st to 10thDay
37%7%12%24%17%3
1800
11th to 20thDay
37%7%10%25%19%2
1800
21st to endDay
37%5%10%25%20%3
1980
November1st to 10thDay
33%6%12%24%22%4
1828
11th to 20thDay
38%412%21%21%4
1611
21st to endDay
39%5%12%27%15%1
1520
December1st to 10thDay
46%7%14%22%10%1
1520
11th to 20thDay
41%6%12%29%9%3
1906
21st to endDay
44%9%17%20%9%1
2772
January1st to 10thNight
39%7%11%23%16%4
2533
11th to 20thNight
44%6%14%21%12%2
2430
21st to endNight
41%5%12%25%14%2
2574
February1st to 10thNight
42%7%13%23%13%2
2340
11th to 20thNight
45%5%11%20%15%4
2275
21st to endNight
46%6%11%20%12%5%
1753
March1st to 10thNight
36%5%12%28%16%2
1980
11th to 20thNight
40%6%11%22%17%3
1980
21st to endNight
43%5%12%20%15%4
2178
April1st to 10thNight
43%7%10%19%17%4
1811
11th to 20thNight
37%7%12%21%17%6%
1775
21st to endNight
39%7%13%25%13%4
1774
May1st to 10thNight
42%8%12%21%13%4
1620
11th to 20thNight
44%9%12%19%15%1
1553
21st to endNight
36%10%18%24%11%1
1551
June1st to 10thNight
33%10%11%27%17%2
1440
11th to 20thNight
36%12%13%23%14%2
1440
21st to endNight
32%9%16%25%17%2
1440
July1st to 10thNight
37%11%16%20%13%4
1400
11th to 20thNight
32%10%17%22%17%3
1541
21st to endNight
29%14%18%23%16%1
1672
August1st to 10thNight
37%10%15%23%14%1
1600
11th to 20thNight
37%10%14%24%15%1
1616
21st to endNight
36%10%13%24%15%3
1980
September1st to 10thNight
38%8%12%20%18%4
1800
11th to 20thNight
34%5%10%26%22%2
1839
21st to endNight
40%7%11%21%19%2
2057
October1st to 10thNight
39%6%12%24%17%2
2160
11th to 20thNight
33%6%11%26%22%2
2160
21st to endNight
34%6%10%25%23%2
2376
November1st to 10thNight
32%5%12%26%20%5%
2249
11th to 20thNight
37%5%9%24%20%5%
2565
21st to endNight
38%6%12%24%18%3
2660
December1st to 10thNight
44%7%11%26%12%1
2660
11th to 20thNight
42%5%11%23%16%2
3288
21st to endNight
42%11%16%19%11%1
4884

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%30%27%15%5%1
234
11th to 20thDay
24%24%33%15%4
258
21st to endDay
23%26%33%12%5%1
264
February1st to 10thDay
28%23%33%12%5%
240
11th to 20thDay
30%26%34%9%
240
21st to endDay
28%20%31%19%2
337
March1st to 10thDay
20%25%26%27%2
420
11th to 20thDay
20%22%31%17%6%2
420
21st to endDay
19%17%34%21%7%1
462
April1st to 10thDay
21%19%27%23%10%1
420
11th to 20thDay
14%16%28%22%13%7%
412
21st to endDay
25%14%26%23%10%2
420
May1st to 10thDay
21%17%26%20%13%4
423
11th to 20thDay
21%12%26%21%15%5%
447
21st to endDay
20%6%20%24%21%9%
485
June1st to 10thDay
16%6%25%26%20%8%
450
11th to 20thDay
14%8%25%28%18%8%
450
21st to endDay
12%424%31%22%8%
450
July1st to 10thDay
11%416%27%26%17%
445
11th to 20thDay
6%214%32%32%13%
444
21st to endDay
11%416%31%27%10%
488
August1st to 10thDay
12%317%26%28%15%
446
11th to 20thDay
11%414%28%28%14%
439
21st to endDay
9%418%25%28%17%
495
September1st to 10thDay
19%418%22%25%13%
450
11th to 20thDay
15%315%28%26%13%
450
21st to endDay
24%8%17%28%16%6%
450
October1st to 10thDay
19%6%18%28%22%8%
450
11th to 20thDay
16%12%27%27%15%4
450
21st to endDay
17%13%30%26%12%3
495
November1st to 10thDay
16%12%25%29%15%3
441
11th to 20thDay
21%13%29%25%12%
271
21st to endDay
16%21%33%22%7%1
180
December1st to 10thDay
18%23%30%22%6%2
180
11th to 20thDay
21%18%31%23%7%
180
21st to endDay
20%14%32%24%11%
198
January1st to 10thNight
18%16%40%22%4
760
11th to 20thNight
22%14%32%29%4
748
21st to endNight
18%15%42%23%2
792
February1st to 10thNight
17%18%35%27%2
720
11th to 20thNight
21%20%37%20%2
703
21st to endNight
23%17%38%19%3
592
March1st to 10thNight
17%16%40%24%4
720
11th to 20thNight
22%17%33%22%6%1
720
21st to endNight
17%13%42%23%5%1
792
April1st to 10thNight
20%18%32%26%5%
720
11th to 20thNight
16%11%34%30%9%1
711
21st to endNight
19%10%30%33%7%1
694
May1st to 10thNight
21%6%28%31%14%1
540
11th to 20thNight
20%427%36%13%1
491
21st to endNight
14%319%41%22%2
389
June1st to 10thNight
11%323%37%26%1
360
11th to 20thNight
12%318%43%21%3
360
21st to endNight
7%121%51%19%1
360
July1st to 10thNight
11%314%40%27%5%
350
11th to 20thNight
6%212%39%38%4
497
21st to endNight
9%212%44%30%3
591
August1st to 10thNight
10%111%43%32%3
537
11th to 20thNight
11%213%36%35%4
552
21st to endNight
13%214%39%28%4
792
September1st to 10thNight
17%213%35%29%4
720
11th to 20thNight
13%317%33%30%3
720
21st to endNight
19%322%32%23%1
720
October1st to 10thNight
21%5%20%29%22%3
720
11th to 20thNight
17%8%26%37%13%1
720
21st to endNight
17%9%32%31%11%
792
November1st to 10thNight
14%8%31%34%12%1
740
11th to 20thNight
17%15%28%31%8%1
760
21st to endNight
16%14%31%31%8%
760
December1st to 10thNight
19%14%34%27%6%
760
11th to 20thNight
18%9%39%30%4
760
21st to endNight
18%11%33%35%3
836
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Copyright 2024 Attilla Danko


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