Cadmus Homestead Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cadmus Homestead Observatory clear sky chart from 2005-11-06 to 2024-02-10.

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
33%
23317
20%
80067
10%
23222
44%
23222
21%
50523

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
16%
751
22%
4346
8%
737
36%
737
11%
2505
January11th to 20thNight
21%
760
22%
4181
6%
740
37%
740
10%
2513
January21st to endNight
18%
831
14%
4475
6%
814
37%
814
11%
2900
February1st to 10thNight
21%
759
19%
2464
8%
759
35%
759
17%
1595
February11th to 20thNight
12%
703
19%
2192
3%
700
32%
700
15%
1456
February21st to endNight
15%
592
23%
1776
7%
592
35%
592
16%
1188
March1st to 10thNight
21%
720
23%
2099
8%
720
39%
720
23%
1306
March11th to 20thNight
21%
720
21%
1980
8%
720
34%
720
21%
1332
March21st to endNight
21%
792
22%
2091
7%
792
33%
792
24%
1407
April1st to 10thNight
19%
720
19%
1800
3%
720
28%
720
21%
1232
April11th to 20thNight
28%
711
19%
1775
6%
711
34%
711
27%
1188
April21st to endNight
27%
720
20%
1800
4%
720
36%
720
26%
1225
May1st to 10thNight
34%
564
16%
1644
7%
564
41%
564
21%
1127
May11th to 20thNight
35%
354
18%
1416
11%
354
46%
354
15%
910
May21st to endNight
45%
388
15%
1551
14%
388
51%
388
20%
956
June1st to 10thNight
45%
360
19%
1440
17%
360
56%
360
21%
863
June11th to 20thNight
45%
360
16%
1440
14%
360
55%
360
22%
865
June21st to endNight
56%
360
17%
1440
19%
360
63%
360
28%
816
July1st to 10thNight
52%
350
14%
1400
15%
350
57%
350
19%
871
July11th to 20thNight
61%
348
17%
1392
19%
348
65%
348
27%
768
July21st to endNight
57%
492
16%
1579
14%
465
62%
465
27%
973
August1st to 10thNight
62%
537
17%
1600
13%
534
65%
534
30%
1008
August11th to 20thNight
55%
634
17%
1698
11%
634
56%
634
27%
1153
August21st to endNight
55%
792
18%
1980
9%
792
57%
792
34%
1299
September1st to 10thNight
47%
720
22%
1800
9%
720
52%
720
31%
1195
September11th to 20thNight
55%
720
30%
1800
20%
720
59%
720
38%
1120
September21st to endNight
48%
720
23%
2030
17%
720
54%
720
26%
1347
October1st to 10thNight
43%
720
18%
2160
14%
720
50%
720
25%
1395
October11th to 20thNight
39%
720
23%
2160
16%
720
49%
720
28%
1325
October21st to endNight
31%
792
26%
2393
14%
792
47%
792
26%
1476
November1st to 10thNight
38%
740
25%
2407
15%
740
53%
740
29%
1360
November11th to 20thNight
30%
760
25%
2471
13%
760
44%
760
22%
1518
November21st to endNight
28%
760
21%
2660
10%
760
43%
760
22%
1574
December1st to 10thNight
21%
760
18%
2660
7%
760
36%
760
15%
1757
December11th to 20thNight
23%
760
18%
3193
8%
759
38%
759
15%
2002
December21st to endNight
24%
827
12%
4774
8%
817
38%
817
11%
2998

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
15%7%35%5%35%5%6%7%39%
78255
Night
16%6%35%5%3445%7%41%
80688
TransparencyDay
43%5%12%23%14%2
77966
Night
42%5%12%24%15%2
80511
SeeingDay
21%14%28%22%11%4
13854
Night
20%12%29%28%11%1
23341

By Month

Percentage Cloud Cover NE (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
15%9%25%435%5%5%6%41%
2517
11th to 20thDay
15%11%5%9%6%345%46%31%
2662
21st to endDay
20%11%47%6%34445%32%
3124
February1st to 10thDay
16%8%45%6%35%6%5%7%36%
1701
11th to 20thDay
15%8%37%5%4446%7%37%
1654
21st to endDay
20%9%37%5%35%435%35%
1480
March1st to 10thDay
13%5%36%5%35%45%7%44%
1855
11th to 20thDay
17%7%36%6%35%5%6%7%36%
1980
21st to endDay
21%7%35%5%33446%37%
2263
April1st to 10thDay
16%7%36%5%345%48%39%
2160
11th to 20thDay
16%7%35%5%2446%7%42%
2134
21st to endDay
18%6%25%6%35%5%6%8%38%
2160
May1st to 10thDay
18%7%26%6%35%5%5%8%35%
2332
11th to 20thDay
20%6%35%5%345%5%7%35%
2478
21st to endDay
15%6%35%5%45%5%6%7%39%
2725
June1st to 10thDay
13%5%35%5%45%6%6%10%37%
2520
11th to 20thDay
14%6%25%5%46%5%7%9%38%
2520
21st to endDay
11%4246%35%6%6%11%41%
2520
July1st to 10thDay
10%5%25%6%46%6%8%10%36%
2520
11th to 20thDay
8%5%26%5%46%7%6%9%43%
2520
21st to endDay
10%6%36%7%46%6%6%8%39%
2642
August1st to 10thDay
11%5%25%7%46%6%8%9%37%
2327
11th to 20thDay
13%5%35%5%45%5%7%9%39%
2183
21st to endDay
13%5%25%5%345%7%9%41%
2376
September1st to 10thDay
16%6%25%425%45%6%44%
2160
11th to 20thDay
13%42443446%7%50%
2160
21st to endDay
18%7%36%5%3445%6%40%
1925
October1st to 10thDay
19%6%24425%45%7%43%
1800
11th to 20thDay
18%5%35%434446%44%
1800
21st to endDay
19%7%25%42445%7%41%
1962
November1st to 10thDay
14%7%24323447%50%
1671
11th to 20thDay
17%5%245%245%5%7%44%
1706
21st to endDay
17%5%35%5%35%5%6%8%41%
1520
December1st to 10thDay
19%9%25%7%35%5%5%6%35%
1520
11th to 20thDay
21%6%344345%48%38%
1906
21st to endDay
19%8%37%6%346%6%7%31%
2772
January1st to 10thNight
16%7%35%5%345%5%8%40%
4429
11th to 20thNight
18%9%35%43445%7%38%
4280
21st to endNight
23%9%37%5%23345%35%
4532
February1st to 10thNight
17%8%36%5%25%5%5%7%39%
2464
11th to 20thNight
17%7%36%5%35%45%6%39%
2190
21st to endNight
19%7%36%5%345%46%39%
1776
March1st to 10thNight
15%5%245%35%45%8%45%
2089
11th to 20thNight
17%9%345%3445%443%
1979
21st to endNight
18%7%3443445%7%41%
2091
April1st to 10thNight
17%6%35%6%35%46%8%38%
1800
11th to 20thNight
15%5%25%5%3445%8%43%
1775
21st to endNight
19%6%25%42346%6%43%
1800
May1st to 10thNight
19%7%25%5%346%47%38%
1644
11th to 20thNight
19%6%35%6%45%45%7%37%
1415
21st to endNight
15%5%35%435%5%6%8%40%
1550
June1st to 10thNight
15%5%36%425%45%8%42%
1440
11th to 20thNight
14%425%445%5%7%8%41%
1440
21st to endNight
12%425%335%6%6%9%45%
1440
July1st to 10thNight
10%6%36%6%46%7%7%8%37%
1440
11th to 20thNight
8%425%5%36%5%7%10%45%
1440
21st to endNight
10%5%35%6%36%6%7%9%41%
1672
August1st to 10thNight
10%5%26%6%35%5%8%9%41%
1611
11th to 20thNight
12%5%36%6%46%6%5%6%41%
1698
21st to endNight
12%6%24435%5%7%8%43%
1980
September1st to 10thNight
14%6%25%5%34347%46%
1800
11th to 20thNight
14%42342445%6%52%
1800
21st to endNight
17%6%25%435%5%5%5%43%
2030
October1st to 10thNight
20%6%25%433346%44%
2160
11th to 20thNight
17%6%24433446%47%
2160
21st to endNight
19%6%2442335%7%45%
2393
November1st to 10thNight
12%5%24425%45%6%52%
2407
11th to 20thNight
15%7%445%24446%46%
2471
21st to endNight
15%425%4345%5%8%44%
2660
December1st to 10thNight
19%8%36%5%35%45%7%36%
2660
11th to 20thNight
18%6%35%5%35%5%5%7%39%
3288
21st to endNight
18%7%36%5%445%6%7%34%
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
44%413%26%10%3
2518
11th to 20thDay
53%5%10%17%13%2
2662
21st to endDay
55%411%21%8%1
3124
February1st to 10thDay
47%6%13%22%11%1
1701
11th to 20thDay
47%5%10%24%13%2
1663
21st to endDay
52%48%22%11%3
1480
March1st to 10thDay
41%413%27%13%2
1858
11th to 20thDay
46%5%10%20%14%4
1980
21st to endDay
49%48%20%17%3
2263
April1st to 10thDay
44%410%22%15%5%
2160
11th to 20thDay
41%411%22%16%5%
2134
21st to endDay
43%5%11%21%16%5%
2160
May1st to 10thDay
46%6%9%21%15%3
2332
11th to 20thDay
47%6%11%21%13%2
2482
21st to endDay
42%8%14%22%13%2
2725
June1st to 10thDay
41%7%13%23%14%2
2520
11th to 20thDay
42%7%14%24%11%3
2520
21st to endDay
36%7%15%26%15%1
2520
July1st to 10thDay
41%7%13%23%15%2
2450
11th to 20thDay
35%7%15%26%16%2
2445
21st to endDay
41%7%12%22%16%2
2494
August1st to 10thDay
41%8%12%24%15%1
2314
11th to 20thDay
41%6%14%22%16%1
2183
21st to endDay
38%7%13%23%16%3
2376
September1st to 10thDay
41%6%11%21%18%4
2160
11th to 20thDay
33%5%9%27%22%4
2160
21st to endDay
46%5%8%19%21%2
1925
October1st to 10thDay
41%413%25%16%1
1800
11th to 20thDay
41%411%24%19%2
1800
21st to endDay
42%411%25%17%2
1962
November1st to 10thDay
35%414%25%18%4
1671
11th to 20thDay
40%411%24%19%2
1706
21st to endDay
40%5%12%31%10%2
1520
December1st to 10thDay
49%416%19%11%1
1520
11th to 20thDay
46%414%28%8%1
1906
21st to endDay
51%5%14%21%9%1
2772
January1st to 10thNight
43%412%27%10%3
4429
11th to 20thNight
45%5%12%24%12%2
4280
21st to endNight
51%39%26%9%1
4532
February1st to 10thNight
45%413%25%11%2
2464
11th to 20thNight
47%49%21%17%3
2192
21st to endNight
47%48%22%16%3
1776
March1st to 10thNight
38%412%26%17%3
2099
11th to 20thNight
44%410%22%16%3
1980
21st to endNight
43%49%20%19%4
2091
April1st to 10thNight
44%410%22%16%4
1800
11th to 20thNight
40%6%10%21%21%3
1775
21st to endNight
41%5%11%21%17%5%
1800
May1st to 10thNight
46%6%10%20%15%3
1644
11th to 20thNight
46%7%11%15%19%3
1416
21st to endNight
41%7%15%19%15%3
1551
June1st to 10thNight
40%6%11%22%19%2
1440
11th to 20thNight
39%7%14%25%14%2
1440
21st to endNight
34%7%15%28%15%2
1440
July1st to 10thNight
42%8%14%19%14%3
1400
11th to 20thNight
33%7%16%27%15%2
1392
21st to endNight
36%9%15%22%16%2
1579
August1st to 10thNight
37%7%15%24%16%1
1600
11th to 20thNight
43%6%14%19%17%2
1698
21st to endNight
37%6%14%22%18%3
1980
September1st to 10thNight
39%5%10%23%18%4
1800
11th to 20thNight
32%5%9%25%25%4
1800
21st to endNight
41%6%8%20%22%3
2030
October1st to 10thNight
43%410%25%16%2
2160
11th to 20thNight
38%411%29%16%2
2160
21st to endNight
39%310%28%18%2
2393
November1st to 10thNight
33%5%12%27%19%4
2407
11th to 20thNight
40%49%25%18%4
2471
21st to endNight
38%413%29%14%1
2660
December1st to 10thNight
48%412%22%13%1
2660
11th to 20thNight
44%5%12%22%14%3
3288
21st to endNight
47%6%14%24%9%
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
28%26%27%14%41
180
11th to 20thDay
33%24%30%11%2
222
21st to endDay
24%30%29%13%21
297
February1st to 10thDay
29%23%31%13%3
267
11th to 20thDay
31%21%38%7%2
321
21st to endDay
34%19%31%15%1
346
March1st to 10thDay
25%22%32%19%2
420
11th to 20thDay
26%26%31%13%31
420
21st to endDay
29%22%28%15%5%2
462
April1st to 10thDay
25%22%30%15%6%1
420
11th to 20thDay
24%21%27%19%7%3
412
21st to endDay
29%15%35%15%42
420
May1st to 10thDay
28%17%27%18%8%2
423
11th to 20thDay
23%15%31%21%8%2
447
21st to endDay
20%6%28%25%18%4
485
June1st to 10thDay
16%12%30%25%13%3
450
11th to 20thDay
20%10%28%25%14%3
450
21st to endDay
14%11%32%27%12%5%
450
July1st to 10thDay
13%5%22%30%21%9%
445
11th to 20thDay
7%5%24%34%24%6%
444
21st to endDay
11%6%30%31%17%5%
488
August1st to 10thDay
11%6%24%29%20%9%
446
11th to 20thDay
15%5%20%29%20%10%
439
21st to endDay
13%5%24%32%15%11%
495
September1st to 10thDay
19%8%20%26%19%8%
450
11th to 20thDay
14%6%22%29%16%12%
450
21st to endDay
23%12%24%22%16%4
450
October1st to 10thDay
23%9%23%24%16%5%
450
11th to 20thDay
19%15%28%23%13%2
450
21st to endDay
22%15%33%20%9%2
486
November1st to 10thDay
19%13%28%25%12%3
365
11th to 20thDay
20%20%30%22%7%
366
21st to endDay
23%21%36%14%6%1
180
December1st to 10thDay
26%22%34%12%5%1
180
11th to 20thDay
29%23%30%14%31
180
21st to endDay
26%23%26%18%6%1
198
January1st to 10thNight
20%19%39%19%3
760
11th to 20thNight
27%17%31%22%3
760
21st to endNight
19%19%38%21%2
836
February1st to 10thNight
23%17%34%24%2
759
11th to 20thNight
25%22%36%15%2
703
21st to endNight
25%21%35%16%3
592
March1st to 10thNight
21%18%36%22%4
720
11th to 20thNight
25%19%32%18%6%1
720
21st to endNight
22%16%37%20%5%
792
April1st to 10thNight
24%20%33%19%4
720
11th to 20thNight
19%15%34%24%7%
711
21st to endNight
23%13%32%25%7%
720
May1st to 10thNight
25%10%28%29%8%
564
11th to 20thNight
20%8%31%32%9%1
354
21st to endNight
17%6%24%37%15%2
389
June1st to 10thNight
17%426%37%15%
360
11th to 20thNight
14%7%27%40%13%
360
21st to endNight
11%324%49%12%1
360
July1st to 10thNight
11%420%43%21%2
350
11th to 20thNight
8%322%41%26%1
348
21st to endNight
11%319%41%25%1
492
August1st to 10thNight
11%314%43%26%3
537
11th to 20thNight
15%414%37%27%2
634
21st to endNight
15%419%36%25%2
792
September1st to 10thNight
16%423%33%21%3
720
11th to 20thNight
14%5%18%33%26%4
720
21st to endNight
20%6%20%33%21%1
720
October1st to 10thNight
22%7%23%28%17%3
720
11th to 20thNight
20%10%26%31%13%
720
21st to endNight
23%12%28%27%10%
792
November1st to 10thNight
16%10%31%30%12%1
740
11th to 20thNight
20%17%28%27%7%1
760
21st to endNight
18%16%33%25%7%
760
December1st to 10thNight
26%15%32%20%6%
760
11th to 20thNight
20%16%35%24%4
760
21st to endNight
22%15%33%28%1
836
Page generated at 2024-02-07 06:11:54. Version ac07

Copyright 2024 Attilla Danko


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