This page made possible by the sponsorship of: Albany Area Amateur Astronomers.

George Landis Arboretum
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the George Landis Arboretum clear sky chart from 2005-11-06 to 2024-01-16.

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
27%
22875
14%
74756
8%
22833
36%
22833
15%
52571

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
14%
2649
4%
757
23%
757
9%
1911
January11th to 20thNight
14%
741
9%
2591
2%
741
23%
741
8%
1990
January21st to endNight
14%
792
13%
2691
5%
792
25%
792
10%
1968
February1st to 10thNight
9%
720
10%
2340
2%
720
19%
720
8%
1809
February11th to 20thNight
12%
703
11%
2149
2%
700
23%
700
8%
1633
February21st to endNight
13%
592
13%
1776
5%
592
24%
592
10%
1355
March1st to 10thNight
14%
720
14%
2160
6%
720
25%
720
12%
1614
March11th to 20thNight
16%
720
15%
2055
6%
720
25%
720
13%
1540
March21st to endNight
20%
792
19%
2007
5%
792
31%
792
15%
1464
April1st to 10thNight
18%
720
14%
1800
3%
720
24%
720
14%
1354
April11th to 20thNight
23%
711
15%
1775
4%
711
29%
711
19%
1297
April21st to endNight
24%
661
16%
1741
5%
661
31%
661
19%
1268
May1st to 10thNight
23%
480
13%
1560
7%
480
30%
480
13%
1149
May11th to 20thNight
30%
354
18%
1416
10%
354
44%
354
16%
900
May21st to endNight
39%
388
14%
1551
11%
388
49%
388
20%
962
June1st to 10thNight
38%
360
16%
1440
12%
360
51%
360
18%
890
June11th to 20thNight
44%
360
15%
1440
16%
360
51%
360
21%
871
June21st to endNight
46%
360
14%
1440
14%
360
55%
360
22%
848
July1st to 10thNight
49%
350
14%
1400
15%
350
58%
350
23%
802
July11th to 20thNight
51%
348
15%
1392
18%
348
56%
348
24%
800
July21st to endNight
53%
394
18%
1486
20%
372
59%
372
23%
866
August1st to 10thNight
51%
388
18%
1452
16%
386
57%
386
25%
854
August11th to 20thNight
50%
669
15%
1733
8%
669
52%
669
27%
1190
August21st to endNight
49%
792
19%
1980
9%
792
53%
792
32%
1314
September1st to 10thNight
46%
720
19%
1800
7%
720
51%
720
31%
1193
September11th to 20thNight
47%
720
25%
1862
15%
720
53%
720
35%
1156
September21st to endNight
45%
720
23%
1980
15%
720
52%
720
28%
1291
October1st to 10thNight
34%
720
15%
2108
10%
720
40%
720
19%
1466
October11th to 20thNight
31%
720
16%
2160
9%
720
40%
720
19%
1481
October21st to endNight
22%
792
13%
2542
7%
792
31%
792
13%
1860
November1st to 10thNight
29%
740
19%
2407
11%
740
40%
740
18%
1593
November11th to 20thNight
24%
760
18%
2470
10%
760
35%
760
13%
1748
November21st to endNight
23%
760
13%
2648
7%
760
32%
760
12%
1874
December1st to 10thNight
14%
760
10%
2660
3%
760
23%
760
8%
2053
December11th to 20thNight
17%
760
9%
3247
3%
759
25%
759
6%
2454
December21st to endNight
13%
828
6%
4848
2%
817
21%
817
4%
3753

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%9%47%6%45%5%5%7%33%
74782
Night
16%9%47%6%45%5%5%7%33%
75004
TransparencyDay
49%8%11%20%11%1
74487
Night
49%8%12%20%11%1
74833
SeeingDay
23%19%28%18%9%3
13671
Night
21%18%27%24%8%1
22884

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
14%12%5%8%7%5%6%7%7%5%24%
1517
11th to 20thDay
15%12%5%9%9%5%6%5%5%5%23%
1480
21st to endDay
12%10%5%11%8%46%6%5%7%26%
1661
February1st to 10thDay
15%11%6%9%9%5%8%6%5%6%20%
1620
11th to 20thDay
10%12%6%11%9%5%7%5%45%26%
1697
21st to endDay
17%11%6%10%8%35%436%25%
1480
March1st to 10thDay
13%9%5%10%7%35%5%5%7%29%
1797
11th to 20thDay
16%11%48%7%345%5%6%30%
1902
21st to endDay
18%10%47%6%34335%36%
2348
April1st to 10thDay
16%10%48%7%35%45%5%33%
2160
11th to 20thDay
16%8%37%6%45%5%5%5%37%
2134
21st to endDay
20%9%47%6%3445%6%32%
2218
May1st to 10thDay
19%10%38%6%35%45%6%30%
2416
11th to 20thDay
18%7%25%5%35%5%5%8%38%
2478
21st to endDay
12%6%26%7%46%5%6%8%38%
2725
June1st to 10thDay
16%7%36%6%35%5%7%9%33%
2520
11th to 20thDay
16%7%36%6%35%6%6%9%33%
2520
21st to endDay
13%7%37%6%46%6%6%10%32%
2520
July1st to 10thDay
11%5%36%7%36%7%7%9%36%
2520
11th to 20thDay
11%5%25%6%46%7%8%10%37%
2520
21st to endDay
12%5%36%7%46%6%7%9%36%
2744
August1st to 10thDay
10%5%26%6%47%7%6%10%37%
2472
11th to 20thDay
11%6%28%7%5%7%6%6%9%34%
2148
21st to endDay
13%6%25%6%36%6%7%9%39%
2376
September1st to 10thDay
13%6%26%5%35%6%6%7%42%
2160
11th to 20thDay
13%5%25%4345%5%8%46%
2098
21st to endDay
13%6%35%5%345%7%8%40%
1980
October1st to 10thDay
19%9%36%6%45%6%5%5%33%
1850
11th to 20thDay
15%7%47%6%345%6%8%36%
1800
21st to endDay
22%10%37%6%35%6%5%8%26%
1812
November1st to 10thDay
14%9%36%43445%8%40%
1671
11th to 20thDay
15%9%47%8%3445%8%33%
1710
21st to endDay
16%11%38%6%445%6%6%30%
1530
December1st to 10thDay
18%16%5%9%8%45%6%5%5%20%
1520
11th to 20thDay
19%12%5%8%7%345%47%26%
1906
21st to endDay
21%15%9%7%6%35%446%18%
2772
January1st to 10thNight
14%12%5%8%7%46%6%6%8%27%
2649
11th to 20thNight
16%13%5%9%7%45%6%6%7%22%
2591
21st to endNight
11%11%6%9%8%46%6%6%7%26%
2691
February1st to 10thNight
15%12%6%10%8%45%6%5%7%22%
2340
11th to 20thNight
12%10%5%11%8%47%6%5%7%25%
2147
21st to endNight
16%11%5%9%7%45%5%5%8%26%
1776
March1st to 10thNight
14%11%410%6%47%45%7%29%
2150
11th to 20thNight
16%11%5%7%7%45%45%5%30%
2054
21st to endNight
16%10%46%6%35%45%6%35%
2007
April1st to 10thNight
18%9%47%6%45%5%47%31%
1800
11th to 20thNight
19%9%36%6%35%5%46%35%
1775
21st to endNight
20%8%25%5%35%5%47%35%
1741
May1st to 10thNight
22%10%47%436%445%30%
1560
11th to 20thNight
18%7%25%5%35%5%5%7%37%
1415
21st to endNight
12%6%35%6%36%5%6%9%39%
1550
June1st to 10thNight
17%6%36%435%5%5%8%39%
1440
11th to 20thNight
16%6%345%235%5%10%41%
1440
21st to endNight
11%425%6%445%6%10%43%
1440
July1st to 10thNight
11%5%35%6%45%46%10%43%
1440
11th to 20thNight
11%6%25%445%5%7%10%42%
1440
21st to endNight
11%5%35%5%346%7%8%43%
1574
August1st to 10thNight
9%425%5%35%6%7%10%44%
1462
11th to 20thNight
11%6%27%6%45%6%7%9%37%
1733
21st to endNight
13%6%25%4245%6%8%45%
1980
September1st to 10thNight
13%5%26%5%3445%7%46%
1800
11th to 20thNight
13%5%2443335%7%51%
1862
21st to endNight
13%5%36%43445%7%45%
1980
October1st to 10thNight
20%7%36%5%3445%7%36%
2108
11th to 20thNight
15%8%26%6%45%5%5%7%38%
2160
21st to endNight
22%9%46%5%345%5%8%28%
2542
November1st to 10thNight
14%8%47%6%3445%6%39%
2407
11th to 20thNight
16%8%38%6%45%46%7%32%
2470
21st to endNight
14%10%47%6%46%5%5%7%31%
2648
December1st to 10thNight
17%13%6%8%7%46%5%6%7%23%
2660
11th to 20thNight
19%10%5%10%7%46%6%5%6%24%
3288
21st to endNight
24%13%8%6%5%345%5%6%20%
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
56%7%12%17%9%
1518
11th to 20thDay
60%8%10%13%7%2
1480
21st to endDay
56%7%11%16%8%2
1661
February1st to 10thDay
63%8%9%13%6%1
1620
11th to 20thDay
58%7%9%17%8%1
1706
21st to endDay
60%6%9%14%11%1
1480
March1st to 10thDay
52%7%12%18%10%2
1800
11th to 20thDay
53%6%10%16%12%3
1902
21st to endDay
52%48%16%16%4
2348
April1st to 10thDay
52%5%8%22%11%2
2160
11th to 20thDay
48%6%10%20%13%2
2134
21st to endDay
53%6%9%18%11%3
2218
May1st to 10thDay
55%5%8%19%11%2
2416
11th to 20thDay
44%7%10%22%15%2
2482
21st to endDay
43%9%14%23%11%1
2725
June1st to 10thDay
47%9%14%20%11%1
2520
11th to 20thDay
45%9%13%20%11%1
2520
21st to endDay
46%8%13%21%10%1
2520
July1st to 10thDay
42%9%13%22%13%1
2450
11th to 20thDay
38%10%15%26%10%
2445
21st to endDay
43%8%12%23%12%1
2591
August1st to 10thDay
40%10%15%23%11%1
2458
11th to 20thDay
46%8%14%24%8%
2148
21st to endDay
39%10%13%25%13%1
2376
September1st to 10thDay
41%8%11%26%13%1
2160
11th to 20thDay
36%7%11%26%19%1
2098
21st to endDay
40%8%11%25%14%2
1980
October1st to 10thDay
50%7%10%19%12%2
1850
11th to 20thDay
45%7%14%24%9%1
1800
21st to endDay
55%8%12%14%9%1
1812
November1st to 10thDay
42%7%13%25%13%1
1671
11th to 20thDay
49%8%11%18%12%2
1710
21st to endDay
52%7%15%17%7%1
1530
December1st to 10thDay
64%8%10%12%6%1
1520
11th to 20thDay
57%8%14%14%5%1
1906
21st to endDay
66%7%8%13%5%
2772
January1st to 10thNight
53%9%11%16%11%1
2649
11th to 20thNight
58%9%12%12%7%1
2591
21st to endNight
54%7%10%17%10%2
2691
February1st to 10thNight
61%6%10%15%7%1
2340
11th to 20thNight
55%9%11%16%9%1
2149
21st to endNight
57%7%11%15%8%2
1776
March1st to 10thNight
54%7%10%19%9%1
2160
11th to 20thNight
54%7%9%20%9%1
2055
21st to endNight
50%6%9%18%14%3
2007
April1st to 10thNight
52%7%10%19%10%2
1800
11th to 20thNight
49%6%10%21%14%1
1775
21st to endNight
49%7%10%17%14%3
1741
May1st to 10thNight
55%6%7%14%14%3
1560
11th to 20thNight
45%6%10%22%14%2
1416
21st to endNight
40%8%16%22%11%2
1551
June1st to 10thNight
44%5%12%25%12%2
1440
11th to 20thNight
40%7%15%24%13%1
1440
21st to endNight
36%8%15%27%13%
1440
July1st to 10thNight
36%7%15%25%14%2
1400
11th to 20thNight
36%7%17%29%11%
1392
21st to endNight
36%8%13%28%13%2
1486
August1st to 10thNight
34%10%16%30%11%1
1452
11th to 20thNight
40%9%15%26%10%
1733
21st to endNight
37%7%13%29%14%1
1980
September1st to 10thNight
37%7%12%29%14%1
1800
11th to 20thNight
34%5%13%26%22%1
1862
21st to endNight
38%7%11%26%16%2
1980
October1st to 10thNight
48%6%12%21%12%1
2108
11th to 20thNight
44%8%15%21%12%1
2160
21st to endNight
53%8%12%16%10%1
2542
November1st to 10thNight
44%7%10%21%16%2
2407
11th to 20thNight
50%8%10%19%11%2
2470
21st to endNight
49%9%14%20%6%1
2648
December1st to 10thNight
58%10%12%15%6%
2660
11th to 20thNight
57%10%11%14%8%1
3288
21st to endNight
63%9%10%13%5%
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
31%24%28%13%31
180
11th to 20thDay
32%31%27%6%21
170
21st to endDay
23%29%37%6%5%
211
February1st to 10thDay
34%35%27%5%
240
11th to 20thDay
27%36%25%10%1
365
21st to endDay
31%26%30%12%2
346
March1st to 10thDay
28%28%31%10%3
420
11th to 20thDay
30%26%28%11%41
420
21st to endDay
32%26%22%14%5%2
462
April1st to 10thDay
30%28%22%12%7%1
420
11th to 20thDay
25%25%27%13%7%2
412
21st to endDay
33%19%28%12%5%2
420
May1st to 10thDay
33%20%26%13%6%3
423
11th to 20thDay
20%22%30%20%7%1
447
21st to endDay
19%13%30%23%12%4
485
June1st to 10thDay
19%17%32%21%9%2
450
11th to 20thDay
20%15%30%22%10%2
450
21st to endDay
17%17%31%24%10%1
450
July1st to 10thDay
13%10%30%26%17%4
445
11th to 20thDay
13%7%32%30%14%4
444
21st to endDay
12%9%38%27%9%3
488
August1st to 10thDay
9%10%30%26%19%5%
446
11th to 20thDay
16%7%31%25%14%8%
439
21st to endDay
14%15%26%24%16%5%
495
September1st to 10thDay
16%12%26%22%17%7%
450
11th to 20thDay
14%10%28%20%18%10%
450
21st to endDay
18%11%29%23%13%6%
450
October1st to 10thDay
25%13%26%18%14%4
450
11th to 20thDay
24%16%28%22%10%1
450
21st to endDay
28%20%28%17%6%
410
November1st to 10thDay
25%18%22%19%13%2
365
11th to 20thDay
26%26%24%17%5%1
370
21st to endDay
29%25%26%17%21
190
December1st to 10thDay
29%26%27%13%4
180
11th to 20thDay
33%28%28%10%2
180
21st to endDay
27%27%32%10%41
198
January1st to 10thNight
23%28%32%15%2
760
11th to 20thNight
26%25%30%17%3
741
21st to endNight
18%28%34%18%2
792
February1st to 10thNight
24%26%32%16%2
720
11th to 20thNight
23%28%32%16%2
703
21st to endNight
29%26%28%16%2
592
March1st to 10thNight
24%25%33%15%3
720
11th to 20thNight
26%25%30%16%3
720
21st to endNight
24%23%28%19%6%1
792
April1st to 10thNight
26%23%28%20%4
720
11th to 20thNight
24%21%28%20%7%
711
21st to endNight
25%20%27%21%6%
661
May1st to 10thNight
28%14%27%21%8%1
480
11th to 20thNight
21%12%30%29%6%1
354
21st to endNight
16%8%29%32%13%1
389
June1st to 10thNight
19%9%27%33%11%1
360
11th to 20thNight
17%12%22%36%13%
360
21st to endNight
14%7%27%37%14%1
360
July1st to 10thNight
10%7%24%39%19%1
350
11th to 20thNight
14%425%40%17%1
348
21st to endNight
11%5%24%43%15%1
394
August1st to 10thNight
10%329%35%22%1
388
11th to 20thNight
16%5%21%36%19%4
669
21st to endNight
15%8%21%33%20%2
792
September1st to 10thNight
15%7%25%33%19%1
720
11th to 20thNight
15%8%24%29%18%6%
720
21st to endNight
16%10%25%31%16%2
720
October1st to 10thNight
22%13%23%26%14%2
720
11th to 20thNight
21%14%27%28%9%
720
21st to endNight
28%17%28%22%5%
792
November1st to 10thNight
20%18%26%28%7%
740
11th to 20thNight
23%22%26%21%7%1
760
21st to endNight
22%23%28%22%6%
760
December1st to 10thNight
25%26%30%15%4
760
11th to 20thNight
26%25%27%19%3
760
21st to endNight
29%27%26%16%2
836
Page generated at 2024-01-13 01:38:11. Version ac07

Copyright 2024 Attilla Danko


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