Anna Maria College
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Anna Maria College clear sky chart from 2005-11-06 to 2024-01-10.

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
23%
22926
18%
74558
7%
22882
36%
22882
18%
48516

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
11%
760
21%
2647
4%
757
31%
757
16%
1632
January11th to 20thNight
12%
720
16%
2520
2%
720
28%
720
12%
1717
January21st to endNight
14%
792
21%
2772
6%
792
34%
792
16%
1726
February1st to 10thNight
11%
720
16%
2278
3%
720
27%
720
15%
1553
February11th to 20thNight
8%
703
20%
2100
2%
700
28%
700
13%
1398
February21st to endNight
11%
592
23%
1776
6%
592
33%
592
15%
1192
March1st to 10thNight
14%
720
22%
2160
6%
720
33%
720
17%
1420
March11th to 20thNight
15%
720
18%
2088
5%
720
29%
720
16%
1427
March21st to endNight
18%
792
21%
2021
5%
792
31%
792
19%
1402
April1st to 10thNight
16%
720
19%
1800
3%
720
26%
720
18%
1282
April11th to 20thNight
20%
711
16%
1775
3%
711
28%
711
21%
1240
April21st to endNight
16%
555
19%
1635
4%
555
28%
555
17%
1108
May1st to 10thNight
18%
540
13%
1620
5%
540
25%
540
14%
1169
May11th to 20thNight
17%
473
17%
1535
7%
473
28%
473
17%
1020
May21st to endNight
28%
389
13%
1551
9%
388
39%
388
17%
1002
June1st to 10thNight
27%
360
14%
1440
8%
360
42%
360
15%
938
June11th to 20thNight
26%
360
12%
1440
9%
360
37%
360
16%
944
June21st to endNight
35%
360
13%
1440
10%
360
47%
360
22%
857
July1st to 10thNight
41%
350
13%
1400
14%
350
49%
350
21%
864
July11th to 20thNight
43%
348
12%
1392
11%
348
50%
348
19%
879
July21st to endNight
42%
394
18%
1486
15%
372
51%
372
24%
881
August1st to 10thNight
39%
456
16%
1520
10%
454
46%
454
26%
947
August11th to 20thNight
40%
598
16%
1662
8%
598
44%
598
25%
1121
August21st to endNight
45%
792
21%
1980
9%
792
49%
792
34%
1276
September1st to 10thNight
37%
720
19%
1800
7%
720
44%
720
29%
1215
September11th to 20thNight
41%
720
25%
1960
14%
720
49%
720
32%
1208
September21st to endNight
37%
720
25%
1980
14%
720
46%
720
28%
1286
October1st to 10thNight
30%
720
18%
1980
10%
720
38%
720
23%
1348
October11th to 20thNight
28%
720
21%
2205
8%
720
43%
720
24%
1385
October21st to endNight
19%
792
16%
2574
5%
792
31%
792
16%
1752
November1st to 10thNight
25%
740
22%
2407
9%
740
42%
740
22%
1461
November11th to 20thNight
19%
760
24%
2470
8%
760
39%
760
18%
1536
November21st to endNight
16%
760
22%
2471
6%
760
36%
760
18%
1532
December1st to 10thNight
15%
760
19%
2660
5%
760
31%
760
14%
1708
December11th to 20thNight
16%
760
17%
3219
4%
759
32%
759
12%
1981
December21st to endNight
11%
829
14%
4794
3%
817
32%
817
8%
3109

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
17%7%35%5%35%5%5%7%39%
74775
Night
16%7%35%5%3445%6%40%
74888
TransparencyDay
44%6%12%22%15%2
74480
Night
43%6%12%22%15%2
74717
SeeingDay
23%17%32%19%7%2
13879
Night
22%17%34%21%6%1
22933

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
13%7%46%5%4445%7%41%
1509
11th to 20thDay
17%8%36%5%35%6%6%7%34%
1440
21st to endDay
12%8%35%6%35%6%48%41%
1584
February1st to 10thDay
18%7%35%6%45%6%6%6%33%
1678
11th to 20thDay
13%7%37%5%45%5%6%6%39%
1748
21st to endDay
19%10%47%5%34336%36%
1480
March1st to 10thDay
15%8%36%5%35%5%5%6%39%
1797
11th to 20thDay
16%8%36%5%35%5%5%7%37%
1872
21st to endDay
19%8%35%5%35%345%40%
2330
April1st to 10thDay
17%9%36%6%3445%7%37%
2160
11th to 20thDay
17%7%25%5%25%5%6%7%40%
2134
21st to endDay
22%6%36%5%35%5%47%34%
2323
May1st to 10thDay
25%8%36%5%35%45%6%31%
2340
11th to 20thDay
19%6%35%5%3345%7%40%
2375
21st to endDay
15%6%35%5%3445%8%42%
2725
June1st to 10thDay
19%5%36%5%46%5%6%8%34%
2520
11th to 20thDay
17%5%35%5%35%5%6%8%36%
2520
21st to endDay
18%6%26%6%45%5%6%8%33%
2520
July1st to 10thDay
14%6%35%5%45%5%5%8%40%
2520
11th to 20thDay
14%5%25%5%46%6%7%9%38%
2520
21st to endDay
12%6%36%5%35%6%7%8%39%
2744
August1st to 10thDay
11%6%25%7%46%6%7%9%37%
2389
11th to 20thDay
13%6%26%6%45%6%6%8%39%
2234
21st to endDay
12%426%5%36%5%5%9%43%
2376
September1st to 10thDay
14%5%35%5%346%6%7%43%
2160
11th to 20thDay
16%6%24323446%50%
1999
21st to endDay
17%6%3442445%7%45%
1980
October1st to 10thDay
22%7%35%434445%39%
1980
11th to 20thDay
14%7%245%3446%7%45%
1751
21st to endDay
21%7%35%5%245%45%39%
1782
November1st to 10thDay
14%8%35%423445%48%
1671
11th to 20thDay
19%7%23434347%45%
1710
21st to endDay
16%8%35%43445%5%42%
1706
December1st to 10thDay
17%9%36%6%35%446%36%
1520
11th to 20thDay
21%7%24323346%43%
1906
21st to endDay
20%11%46%5%345%5%6%31%
2772
January1st to 10thNight
16%7%35%5%2445%7%43%
2647
11th to 20thNight
18%10%37%5%345%6%6%35%
2520
21st to endNight
12%8%36%5%25%5%6%7%41%
2772
February1st to 10thNight
16%9%36%5%35%5%5%6%37%
2278
11th to 20thNight
13%8%37%5%35%5%5%6%39%
2098
21st to endNight
17%10%35%5%3445%6%38%
1776
March1st to 10thNight
15%8%35%5%445%5%5%41%
2150
11th to 20thNight
15%8%46%445%35%7%38%
2087
21st to endNight
16%9%37%42445%5%40%
2021
April1st to 10thNight
17%8%36%6%45%5%5%6%36%
1800
11th to 20thNight
19%7%26%434447%40%
1775
21st to endNight
21%7%37%5%24446%38%
1635
May1st to 10thNight
23%8%36%5%345%47%31%
1620
11th to 20thNight
19%7%35%5%3445%6%39%
1534
21st to endNight
17%7%36%5%3445%8%39%
1550
June1st to 10thNight
17%7%37%6%35%46%6%37%
1440
11th to 20thNight
19%7%36%435%46%7%36%
1440
21st to endNight
14%5%25%43447%8%43%
1440
July1st to 10thNight
14%6%36%6%345%6%8%40%
1440
11th to 20thNight
15%6%26%435%6%7%8%37%
1440
21st to endNight
11%5%35%6%35%6%5%8%44%
1574
August1st to 10thNight
9%426%7%35%5%6%8%43%
1530
11th to 20thNight
12%6%25%7%45%6%6%9%38%
1662
21st to endNight
14%5%245%2445%7%48%
1980
September1st to 10thNight
14%6%26%4245%5%6%45%
1800
11th to 20thNight
13%6%24424246%52%
1960
21st to endNight
16%6%344235%5%6%46%
1980
October1st to 10thNight
21%7%24433446%41%
1980
11th to 20thNight
15%6%25%4345%47%45%
2205
21st to endNight
21%8%35%5%33346%38%
2574
November1st to 10thNight
14%7%245%3445%5%48%
2407
11th to 20thNight
17%7%34434446%45%
2470
21st to endNight
15%6%35%4345%5%7%43%
2471
December1st to 10thNight
18%10%26%5%34446%39%
2660
11th to 20thNight
19%7%35%4345%6%6%39%
3288
21st to endNight
20%11%46%43445%6%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
42%410%28%12%3
1510
11th to 20thDay
46%8%14%18%12%2
1440
21st to endDay
41%5%14%23%14%3
1584
February1st to 10thDay
48%6%14%18%12%2
1678
11th to 20thDay
45%6%10%22%14%3
1757
21st to endDay
51%49%19%14%2
1480
March1st to 10thDay
44%413%21%14%4
1800
11th to 20thDay
44%5%12%21%15%4
1872
21st to endDay
47%48%18%17%5%
2330
April1st to 10thDay
47%411%21%15%3
2160
11th to 20thDay
42%5%12%21%18%3
2134
21st to endDay
49%5%9%17%16%3
2323
May1st to 10thDay
53%5%9%18%13%2
2340
11th to 20thDay
43%6%10%22%17%3
2379
21st to endDay
41%6%14%23%13%2
2725
June1st to 10thDay
47%7%12%23%10%1
2520
11th to 20thDay
44%8%12%20%15%1
2520
21st to endDay
45%8%12%21%12%1
2520
July1st to 10thDay
42%7%11%23%14%2
2450
11th to 20thDay
40%9%14%25%12%1
2445
21st to endDay
39%7%14%22%14%3
2591
August1st to 10thDay
41%8%14%23%12%1
2375
11th to 20thDay
42%8%14%24%12%1
2234
21st to endDay
38%6%10%26%17%2
2376
September1st to 10thDay
40%6%12%23%18%1
2160
11th to 20thDay
35%5%9%26%23%3
1999
21st to endDay
39%5%9%24%21%2
1980
October1st to 10thDay
47%5%10%22%13%4
1980
11th to 20thDay
37%5%13%28%15%2
1751
21st to endDay
47%413%19%13%3
1782
November1st to 10thDay
40%412%25%17%3
1671
11th to 20thDay
40%5%11%22%20%2
1710
21st to endDay
42%6%13%25%12%2
1706
December1st to 10thDay
48%415%17%15%2
1520
11th to 20thDay
43%314%20%17%2
1906
21st to endDay
52%6%11%20%11%1
2772
January1st to 10thNight
41%5%12%23%16%3
2647
11th to 20thNight
50%6%14%20%8%2
2520
21st to endNight
42%5%12%21%18%3
2772
February1st to 10thNight
47%6%13%20%12%2
2278
11th to 20thNight
45%5%10%21%15%4
2100
21st to endNight
47%410%22%14%4
1776
March1st to 10thNight
43%6%10%24%15%3
2160
11th to 20thNight
45%6%10%18%16%4
2088
21st to endNight
45%49%18%18%5%
2021
April1st to 10thNight
48%5%10%19%16%3
1800
11th to 20thNight
44%6%11%20%18%1
1775
21st to endNight
47%5%10%20%13%5%
1635
May1st to 10thNight
52%7%10%18%11%3
1620
11th to 20thNight
46%6%11%20%14%3
1535
21st to endNight
45%7%13%21%12%1
1551
June1st to 10thNight
47%6%10%23%12%1
1440
11th to 20thNight
47%7%12%21%12%1
1440
21st to endNight
37%8%15%24%14%1
1440
July1st to 10thNight
40%8%13%23%15%1
1400
11th to 20thNight
42%8%15%25%9%1
1392
21st to endNight
36%9%15%25%13%2
1486
August1st to 10thNight
36%9%14%25%13%2
1520
11th to 20thNight
41%8%15%23%12%1
1662
21st to endNight
35%7%12%27%19%1
1980
September1st to 10thNight
40%7%11%24%18%1
1800
11th to 20thNight
34%5%10%23%25%2
1960
21st to endNight
39%6%8%25%19%3
1980
October1st to 10thNight
44%6%12%23%12%4
1980
11th to 20thNight
38%6%14%26%15%1
2205
21st to endNight
49%5%11%21%13%2
2574
November1st to 10thNight
38%6%11%22%20%4
2407
11th to 20thNight
42%411%21%19%3
2470
21st to endNight
39%6%15%26%13%1
2471
December1st to 10thNight
46%5%13%23%13%1
2660
11th to 20thNight
43%5%15%19%16%2
3288
21st to endNight
49%6%10%24%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
24%28%30%15%3
178
11th to 20thDay
29%29%31%8%3
160
21st to endDay
21%30%35%11%3
176
February1st to 10thDay
35%23%30%10%1
318
11th to 20thDay
26%29%35%9%1
416
21st to endDay
34%18%36%10%2
346
March1st to 10thDay
30%22%35%11%2
420
11th to 20thDay
28%27%30%12%31
420
21st to endDay
28%21%33%11%5%2
462
April1st to 10thDay
32%23%28%10%6%1
420
11th to 20thDay
28%17%38%12%5%
412
21st to endDay
32%18%32%14%31
420
May1st to 10thDay
34%20%28%12%5%1
423
11th to 20thDay
23%18%39%16%31
447
21st to endDay
20%12%36%20%10%2
485
June1st to 10thDay
18%11%38%22%10%2
450
11th to 20thDay
18%14%38%21%6%2
450
21st to endDay
17%13%36%22%10%3
450
July1st to 10thDay
19%8%30%28%11%4
445
11th to 20thDay
16%6%30%33%12%3
444
21st to endDay
11%10%37%31%9%1
488
August1st to 10thDay
11%9%32%35%11%2
446
11th to 20thDay
16%7%32%29%13%3
439
21st to endDay
13%12%30%26%15%3
495
September1st to 10thDay
19%10%27%24%15%5%
450
11th to 20thDay
21%10%30%19%12%8%
450
21st to endDay
21%13%32%21%9%4
450
October1st to 10thDay
29%13%26%18%11%3
450
11th to 20thDay
19%20%31%23%6%2
414
21st to endDay
29%17%31%17%6%1
396
November1st to 10thDay
23%18%33%18%7%1
365
11th to 20thDay
28%22%28%17%31
370
21st to endDay
26%23%31%16%5%
366
December1st to 10thDay
24%31%28%14%3
180
11th to 20thDay
36%23%34%5%2
180
21st to endDay
29%26%33%7%41
198
January1st to 10thNight
23%23%39%14%1
760
11th to 20thNight
28%22%34%14%2
720
21st to endNight
21%24%35%17%2
792
February1st to 10thNight
26%22%36%15%1
720
11th to 20thNight
23%26%39%11%1
703
21st to endNight
27%23%35%13%1
592
March1st to 10thNight
24%23%36%16%2
720
11th to 20thNight
23%25%35%16%2
720
21st to endNight
24%22%31%19%3
792
April1st to 10thNight
25%20%36%17%3
720
11th to 20thNight
23%21%33%19%4
711
21st to endNight
25%21%35%17%2
555
May1st to 10thNight
30%17%31%19%2
540
11th to 20thNight
20%18%40%17%4
473
21st to endNight
22%8%37%28%5%
389
June1st to 10thNight
19%8%37%29%7%
360
11th to 20thNight
21%8%39%26%6%
360
21st to endNight
14%442%33%7%
360
July1st to 10thNight
15%7%33%37%8%1
350
11th to 20thNight
18%428%37%12%1
348
21st to endNight
11%5%36%38%9%
394
August1st to 10thNight
10%439%37%10%
456
11th to 20thNight
15%6%32%34%13%1
598
21st to endNight
16%6%26%37%14%2
792
September1st to 10thNight
16%7%34%32%11%1
720
11th to 20thNight
17%8%28%28%16%2
720
21st to endNight
19%9%29%29%11%2
720
October1st to 10thNight
25%13%28%23%9%2
720
11th to 20thNight
20%15%34%20%10%1
720
21st to endNight
29%16%32%17%5%
792
November1st to 10thNight
19%17%36%20%7%1
740
11th to 20thNight
24%24%29%16%5%1
760
21st to endNight
22%22%37%15%41
760
December1st to 10thNight
26%21%34%15%4
760
11th to 20thNight
25%23%35%16%2
760
21st to endNight
26%24%35%14%2
836
Page generated at 2024-01-07 10:06:50. Version ac07

Copyright 2024 Attilla Danko


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