Ohatchee's Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ohatchee's Observatory clear sky chart from 2005-11-06 to 2024-11-08.

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
57%
24181
20%
96781
18%
23945
63%
23945
24%
56483

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
38%
756
24%
3766
13%
737
51%
737
18%
2180
January11th to 20thNight
43%
753
31%
3624
16%
740
52%
740
21%
1933
January21st to endNight
32%
833
18%
4086
12%
814
45%
814
16%
2518
February1st to 10thNight
38%
760
26%
2280
14%
760
47%
760
27%
1431
February11th to 20thNight
35%
741
22%
2219
11%
740
44%
740
27%
1427
February21st to endNight
35%
628
19%
1884
10%
628
42%
628
23%
1253
March1st to 10thNight
42%
757
17%
3730
14%
745
49%
745
16%
2620
March11th to 20thNight
45%
752
21%
3662
13%
740
51%
740
19%
2098
March21st to endNight
50%
623
19%
3362
21%
610
59%
610
20%
1829
April1st to 10thNight
49%
570
24%
1900
20%
570
56%
570
27%
1140
April11th to 20thNight
50%
563
24%
1875
21%
563
58%
563
30%
1075
April21st to endNight
66%
570
31%
1900
31%
570
72%
570
44%
938
May1st to 10thNight
65%
564
19%
3100
25%
559
70%
559
21%
1760
May11th to 20thNight
68%
553
16%
2856
17%
541
71%
541
20%
1615
May21st to endNight
76%
600
18%
3039
23%
593
77%
593
28%
1335
June1st to 10thNight
73%
570
17%
1710
18%
570
74%
570
32%
1046
June11th to 20thNight
79%
570
17%
1710
18%
570
79%
570
35%
1007
June21st to endNight
72%
570
12%
1710
12%
570
72%
570
29%
1076
July1st to 10thNight
76%
536
7%
2763
11%
535
76%
535
17%
1616
July11th to 20thNight
81%
535
6%
3073
13%
533
81%
533
18%
1531
July21st to endNight
80%
605
8%
3295
15%
569
81%
569
15%
2184
August1st to 10thNight
85%
548
19%
2815
14%
544
85%
544
24%
1390
August11th to 20thNight
76%
545
13%
2695
14%
543
77%
543
20%
1388
August21st to endNight
68%
609
10%
3226
17%
605
69%
605
14%
1932
September1st to 10thNight
74%
570
18%
1900
20%
570
74%
570
25%
1200
September11th to 20thNight
66%
746
19%
2076
16%
746
67%
746
29%
1349
September21st to endNight
71%
760
29%
2090
23%
760
73%
760
38%
1241
October1st to 10thNight
68%
760
22%
2678
23%
740
71%
740
27%
1770
October11th to 20thNight
68%
760
37%
2039
30%
740
73%
740
48%
1101
October21st to endNight
60%
836
30%
2536
29%
814
65%
814
35%
1464
November1st to 10thNight
63%
771
29%
2483
27%
771
69%
771
37%
1345
November11th to 20thNight
53%
760
31%
2470
27%
760
61%
760
34%
1367
November21st to endNight
50%
760
27%
2470
21%
760
59%
760
32%
1430
December1st to 10thNight
46%
760
26%
2470
21%
760
54%
760
27%
1488
December11th to 20thNight
41%
759
23%
2906
16%
758
49%
758
21%
1759
December21st to endNight
38%
828
15%
4383
14%
817
46%
817
14%
2647

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
9%5%26%5%5%5%5%7%9%41%
100597
Night
10%6%26%44446%8%45%
98463
TransparencyDay
35%9%14%18%16%8%
104504
Night
34%8%14%18%18%8%
102694
SeeingDay
11%6%19%24%24%16%
14459
Night
11%418%30%27%9%
24368

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
13%6%27%43435%7%46%
3060
11th to 20thDay
10%5%25%32336%7%53%
3160
21st to endDay
23%8%35%433346%38%
3476
February1st to 10thDay
16%8%36%443346%43%
1900
11th to 20thDay
15%6%25%345%36%7%43%
1848
21st to endDay
13%7%36%5%5%6%46%7%38%
1570
March1st to 10thDay
16%9%39%44445%7%34%
3120
11th to 20thDay
11%5%26%44446%9%43%
3265
21st to endDay
13%6%36%44435%7%44%
4165
April1st to 10thDay
10%6%26%445%46%7%46%
2280
11th to 20thDay
11%6%25%45%447%8%44%
2254
21st to endDay
7%415%33445%8%54%
2280
May1st to 10thDay
7%425%445%48%10%46%
3765
11th to 20thDay
13%5%26%5%45%46%7%42%
3953
21st to endDay
4326%45%5%5%8%11%47%
4476
June1st to 10thDay
7%6%37%5%6%7%6%10%11%32%
2470
11th to 20thDay
4425%6%6%7%6%10%12%38%
2470
21st to endDay
8%5%27%6%6%7%7%9%13%31%
2470
July1st to 10thDay
45%28%7%8%9%7%11%14%25%
4120
11th to 20thDay
5%5%27%6%7%7%7%9%12%33%
3806
21st to endDay
35%38%6%8%9%8%12%15%23%
4118
August1st to 10thDay
431446%6%6%9%13%44%
3785
11th to 20thDay
5%426%5%5%6%6%8%11%42%
3729
21st to endDay
6%5%28%8%7%7%6%8%10%33%
4180
September1st to 10thDay
10%5%27%5%6%7%6%8%10%33%
2273
11th to 20thDay
9%7%38%5%6%6%47%8%37%
2090
21st to endDay
7%426%45%5%46%8%50%
2090
October1st to 10thDay
7%425%44345%8%53%
2090
11th to 20thDay
7%31433346%7%58%
2083
21st to endDay
8%5%16%43445%6%54%
2090
November1st to 10thDay
7%5%2444435%7%56%
1754
11th to 20thDay
9%42443336%7%55%
1710
21st to endDay
10%5%26%44336%7%49%
1710
December1st to 10thDay
12%6%37%5%3435%7%46%
1710
11th to 20thDay
13%8%38%44435%6%43%
2153
21st to endDay
16%9%37%433347%40%
3124
January1st to 10thNight
15%6%25%45%5%35%5%44%
3881
11th to 20thNight
13%7%25%433345%51%
3800
21st to endNight
21%10%35%333245%41%
4180
February1st to 10thNight
14%7%26%43335%6%46%
2280
11th to 20thNight
17%7%26%43345%5%44%
2218
21st to endNight
15%8%37%445%36%6%39%
1884
March1st to 10thNight
21%11%38%44335%6%32%
3733
11th to 20thNight
11%7%36%5%45%47%8%41%
3714
21st to endNight
12%7%26%44445%6%46%
3471
April1st to 10thNight
11%6%26%5%4435%7%46%
1900
11th to 20thNight
11%5%25%44447%7%47%
1875
21st to endNight
6%32433335%7%61%
1900
May1st to 10thNight
9%6%28%5%5%447%9%42%
3130
11th to 20thNight
11%6%36%445%45%9%44%
2922
21st to endNight
4324446%47%13%50%
3079
June1st to 10thNight
7%5%25%5%5%5%49%13%40%
1710
11th to 20thNight
3325%45%5%6%9%12%46%
1710
21st to endNight
6%5%15%6%6%6%5%8%12%40%
1710
July1st to 10thNight
3427%5%6%7%7%10%16%34%
2840
11th to 20thNight
2415%45%5%5%8%12%48%
3148
21st to endNight
2327%6%6%7%8%11%16%31%
3435
August1st to 10thNight
221445%6%5%9%14%48%
3144
11th to 20thNight
3316%445%5%8%12%48%
3100
21st to endNight
4426%5%6%6%5%9%11%41%
3476
September1st to 10thNight
7%6%36%45%6%5%8%11%38%
1900
11th to 20thNight
8%5%37%5%6%5%47%8%43%
2076
21st to endNight
7%5%26%44446%8%51%
2090
October1st to 10thNight
5%425%44435%8%55%
2090
11th to 20thNight
6%5%13333347%63%
2092
21st to endNight
9%5%15%343346%57%
2508
November1st to 10thNight
7%5%1434435%6%57%
2483
11th to 20thNight
9%5%26%443346%55%
2470
21st to endNight
10%6%25%44446%8%48%
2470
December1st to 10thNight
11%6%36%5%4335%6%47%
2470
11th to 20thNight
14%7%36%444447%44%
3042
21st to endNight
15%9%38%443345%41%
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
38%5%6%17%21%13%
3061
11th to 20thDay
29%5%8%18%29%11%
3160
21st to endDay
48%5%415%20%9%
3476
February1st to 10thDay
43%48%14%19%11%
1900
11th to 20thDay
39%7%8%16%20%10%
1858
21st to endDay
42%7%10%16%16%9%
1570
March1st to 10thDay
49%7%9%18%13%5%
3120
11th to 20thDay
35%8%12%20%20%5%
3265
21st to endDay
38%6%12%17%17%10%
4165
April1st to 10thDay
36%6%11%17%20%9%
2280
11th to 20thDay
36%6%10%20%19%9%
2254
21st to endDay
27%6%10%24%23%9%
2280
May1st to 10thDay
27%11%17%26%15%4
3800
11th to 20thDay
38%8%14%21%17%1
3957
21st to endDay
26%10%17%33%13%2
4489
June1st to 10thDay
40%12%16%22%9%1
2470
11th to 20thDay
32%13%17%24%11%2
2470
21st to endDay
38%14%22%16%10%1
2470
July1st to 10thDay
42%16%28%12%2
4055
11th to 20thDay
38%15%37%8%1
3742
21st to endDay
42%19%24%13%2
3987
August1st to 10thDay
26%12%19%26%16%1
3773
11th to 20thDay
31%12%19%23%14%1
3765
21st to endDay
42%13%19%15%10%2
4179
September1st to 10thDay
40%12%18%14%11%4
2273
11th to 20thDay
41%10%14%13%14%7%
2090
21st to endDay
32%7%11%21%20%8%
2090
October1st to 10thDay
30%48%11%17%30%
3480
11th to 20thDay
16%35%20%22%33%
3439
21st to endDay
22%45%11%38%19%
3428
November1st to 10thDay
28%49%21%23%15%
1754
11th to 20thDay
28%5%8%17%28%14%
1710
21st to endDay
34%7%7%19%21%12%
1710
December1st to 10thDay
38%6%10%17%21%8%
1710
11th to 20thDay
43%5%6%17%18%11%
2150
21st to endDay
43%6%7%18%20%6%
3124
January1st to 10thNight
40%5%7%10%26%12%
3881
11th to 20thNight
35%46%15%30%10%
3800
21st to endNight
46%45%14%23%8%
4180
February1st to 10thNight
40%47%16%22%11%
2280
11th to 20thNight
41%5%6%14%20%13%
2219
21st to endNight
43%6%10%15%13%13%
1884
March1st to 10thNight
52%6%9%14%13%6%
3733
11th to 20thNight
38%8%11%18%18%8%
3714
21st to endNight
36%5%12%20%17%9%
3471
April1st to 10thNight
37%6%13%13%20%11%
1900
11th to 20thNight
34%5%11%20%21%9%
1875
21st to endNight
23%5%12%29%25%8%
1900
May1st to 10thNight
33%11%17%18%17%4
3160
11th to 20thNight
36%7%15%23%17%2
2923
21st to endNight
22%9%18%34%15%2
3087
June1st to 10thNight
32%9%22%26%9%2
1710
11th to 20thNight
26%12%23%25%13%1
1710
21st to endNight
33%11%26%19%10%1
1710
July1st to 10thNight
33%15%36%13%4
2795
11th to 20thNight
25%15%47%11%2
3089
21st to endNight
33%22%27%15%2
3325
August1st to 10thNight
22%12%27%26%13%1
3132
11th to 20thNight
24%11%26%29%10%
3130
21st to endNight
33%14%22%17%11%3
3476
September1st to 10thNight
35%12%21%15%12%5%
1900
11th to 20thNight
36%10%16%18%14%7%
2076
21st to endNight
29%7%14%24%17%9%
2090
October1st to 10thNight
32%5%8%13%21%22%
3480
11th to 20thNight
14%37%19%27%32%
3475
21st to endNight
19%35%11%45%17%
4120
November1st to 10thNight
28%5%8%17%27%15%
2483
11th to 20thNight
32%45%19%26%14%
2470
21st to endNight
33%6%9%18%22%13%
2470
December1st to 10thNight
37%6%10%19%21%6%
2470
11th to 20thNight
41%47%13%23%12%
3044
21st to endNight
45%5%7%19%20%5%
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
17%14%38%22%8%1
270
11th to 20thDay
13%13%29%30%13%2
270
21st to endDay
21%14%40%19%5%1
297
February1st to 10thDay
20%18%34%20%7%1
270
11th to 20thDay
20%16%34%22%7%1
270
21st to endDay
12%21%41%20%5%
225
March1st to 10thDay
14%15%38%25%7%
270
11th to 20thDay
15%15%35%23%11%
314
21st to endDay
15%11%31%28%13%1
506
April1st to 10thDay
15%12%30%26%15%2
460
11th to 20thDay
12%14%27%25%19%3
452
21st to endDay
8%7%28%32%22%4
460
May1st to 10thDay
7%5%28%30%25%6%
463
11th to 20thDay
9%315%29%28%16%
487
21st to endDay
6%213%31%29%19%
529
June1st to 10thDay
11%29%25%32%21%
490
11th to 20thDay
8%212%20%33%25%
490
21st to endDay
9%9%22%32%27%
490
July1st to 10thDay
8%6%17%32%36%
485
11th to 20thDay
6%1314%33%42%
484
21st to endDay
5%15%16%41%32%
532
August1st to 10thDay
8%316%34%39%
486
11th to 20thDay
10%413%33%39%
479
21st to endDay
9%18%18%32%32%
539
September1st to 10thDay
10%26%16%36%30%
490
11th to 20thDay
13%310%21%34%19%
490
21st to endDay
9%28%27%34%20%
490
October1st to 10thDay
8%318%36%26%9%
490
11th to 20thDay
7%5%16%29%30%13%
483
21st to endDay
14%7%18%34%22%6%
330
November1st to 10thDay
13%5%20%36%23%3
291
11th to 20thDay
13%7%29%30%18%4
270
21st to endDay
12%6%31%30%17%4
270
December1st to 10thDay
17%8%31%28%12%4
270
11th to 20thDay
19%13%33%24%10%1
270
21st to endDay
21%14%27%21%15%1
297
January1st to 10thNight
16%7%32%36%8%
760
11th to 20thNight
15%8%27%36%13%
760
21st to endNight
21%9%32%31%7%
836
February1st to 10thNight
17%10%30%35%9%
760
11th to 20thNight
20%7%33%29%11%
743
21st to endNight
16%12%31%35%5%
628
March1st to 10thNight
15%8%30%35%11%1
760
11th to 20thNight
13%6%30%35%15%2
760
21st to endNight
12%6%26%38%17%1
632
April1st to 10thNight
15%6%24%37%17%1
570
11th to 20thNight
13%5%25%32%23%1
563
21st to endNight
7%418%41%28%2
570
May1st to 10thNight
8%416%40%28%5%
570
11th to 20thNight
6%212%38%35%7%
561
21st to endNight
5%18%29%45%11%
617
June1st to 10thNight
9%7%27%46%11%
570
11th to 20thNight
41421%50%20%
570
21st to endNight
8%15%20%44%22%
570
July1st to 10thNight
4412%50%30%
555
11th to 20thNight
438%45%39%
552
21st to endNight
3212%51%31%
624
August1st to 10thNight
329%47%39%
567
11th to 20thNight
7%39%49%32%
564
21st to endNight
8%16%16%45%23%
627
September1st to 10thNight
9%2416%45%23%
570
11th to 20thNight
11%18%24%43%14%
746
21st to endNight
9%19%28%44%9%
760
October1st to 10thNight
8%115%37%32%6%
760
11th to 20thNight
8%315%35%33%6%
760
21st to endNight
12%417%36%27%3
836
November1st to 10thNight
11%5%16%42%24%3
771
11th to 20thNight
10%7%24%38%19%2
760
21st to endNight
12%5%26%36%17%3
760
December1st to 10thNight
13%7%28%33%18%2
760
11th to 20thNight
20%6%26%32%15%1
760
21st to endNight
22%7%27%33%11%1
836
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