Upstate Stars Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Upstate Stars Observatory clear sky chart from 2005-11-06 to 2024-01-12.

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%
22983
14%
74710
8%
22940
35%
22940
15%
51592

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
12%
760
14%
2649
4%
757
24%
757
10%
1818
January11th to 20thNight
16%
727
10%
2541
4%
727
24%
727
9%
1872
January21st to endNight
13%
792
15%
2624
4%
792
25%
792
11%
1820
February1st to 10thNight
10%
720
10%
2340
2%
720
20%
720
10%
1721
February11th to 20thNight
9%
703
12%
2162
2%
700
21%
700
9%
1560
February21st to endNight
14%
592
17%
1776
7%
592
26%
592
11%
1281
March1st to 10thNight
14%
720
15%
2160
4%
720
27%
720
14%
1491
March11th to 20thNight
18%
720
16%
2012
7%
720
28%
720
15%
1416
March21st to endNight
18%
792
19%
2034
5%
792
29%
792
17%
1445
April1st to 10thNight
16%
720
14%
1800
2%
720
23%
720
14%
1372
April11th to 20thNight
22%
711
15%
1775
3%
711
28%
711
19%
1284
April21st to endNight
24%
716
15%
1796
4%
716
30%
716
19%
1305
May1st to 10thNight
28%
473
14%
1553
9%
473
34%
473
14%
1117
May11th to 20thNight
31%
354
19%
1416
14%
354
42%
354
15%
903
May21st to endNight
42%
388
15%
1551
14%
388
50%
388
18%
970
June1st to 10thNight
40%
360
15%
1440
11%
360
51%
360
18%
885
June11th to 20thNight
44%
360
13%
1440
14%
360
53%
360
19%
895
June21st to endNight
50%
360
14%
1440
12%
360
58%
360
23%
836
July1st to 10thNight
52%
350
13%
1400
16%
350
57%
350
22%
837
July11th to 20thNight
54%
348
15%
1392
19%
348
59%
348
23%
836
July21st to endNight
50%
394
15%
1486
16%
372
55%
372
21%
889
August1st to 10thNight
53%
468
15%
1532
10%
466
57%
466
25%
961
August11th to 20thNight
52%
662
13%
1726
9%
662
53%
662
25%
1215
August21st to endNight
52%
792
18%
1980
9%
792
55%
792
30%
1340
September1st to 10thNight
42%
720
17%
1800
7%
720
46%
720
28%
1232
September11th to 20thNight
46%
720
25%
1840
15%
720
51%
720
32%
1187
September21st to endNight
41%
720
22%
1980
15%
720
47%
720
24%
1323
October1st to 10thNight
33%
720
15%
2142
10%
720
40%
720
19%
1491
October11th to 20thNight
30%
720
16%
2160
9%
720
40%
720
20%
1471
October21st to endNight
20%
792
14%
2496
8%
792
30%
792
13%
1812
November1st to 10thNight
30%
740
20%
2407
11%
740
42%
740
19%
1544
November11th to 20thNight
25%
760
17%
2470
11%
760
34%
760
14%
1698
November21st to endNight
21%
760
15%
2648
7%
760
33%
760
14%
1774
December1st to 10thNight
15%
760
9%
2660
4%
760
21%
760
8%
2016
December11th to 20thNight
15%
760
9%
3241
3%
759
22%
759
7%
2348
December21st to endNight
12%
829
7%
4841
3%
817
22%
817
4%
3627

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
18%9%47%6%35%5%5%7%31%
74735
Night
18%9%47%6%3445%7%33%
74971
TransparencyDay
50%7%12%19%11%2
74440
Night
48%7%14%19%11%1
74800
SeeingDay
26%18%27%17%9%3
13706
Night
24%18%25%23%9%1
22991

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%12%7%9%8%5%5%5%5%6%24%
1517
11th to 20thDay
17%13%6%10%8%36%5%5%5%21%
1448
21st to endDay
12%12%6%10%7%45%5%5%7%26%
1729
February1st to 10thDay
16%13%6%9%9%46%5%5%6%20%
1620
11th to 20thDay
14%10%5%9%8%44448%28%
1685
21st to endDay
21%11%49%8%3445%5%26%
1480
March1st to 10thDay
15%10%5%10%8%3445%7%30%
1797
11th to 20thDay
15%13%5%9%6%3445%6%30%
1944
21st to endDay
20%11%47%6%3445%5%31%
2322
April1st to 10thDay
18%11%5%7%6%3445%5%32%
2160
11th to 20thDay
18%9%36%6%3445%6%35%
2134
21st to endDay
19%11%46%6%44446%32%
2164
May1st to 10thDay
24%10%36%6%3445%5%30%
2421
11th to 20thDay
21%6%36%6%35%5%5%6%33%
2478
21st to endDay
16%6%36%6%36%6%5%7%36%
2725
June1st to 10thDay
18%5%36%6%5%6%47%9%31%
2520
11th to 20thDay
18%7%37%5%45%6%6%9%29%
2520
21st to endDay
18%7%36%6%345%6%10%32%
2520
July1st to 10thDay
13%6%36%6%46%6%6%9%34%
2520
11th to 20thDay
12%6%26%5%46%7%6%10%37%
2520
21st to endDay
14%7%36%6%46%5%6%8%35%
2744
August1st to 10thDay
15%6%26%6%46%6%7%10%33%
2393
11th to 20thDay
15%6%36%7%46%6%6%8%32%
2156
21st to endDay
16%5%35%5%46%6%7%9%35%
2376
September1st to 10thDay
19%6%46%6%3445%8%36%
2160
11th to 20thDay
16%6%25%445%5%5%7%43%
2120
21st to endDay
19%6%35%5%35%5%6%7%36%
1980
October1st to 10thDay
22%8%37%5%345%5%6%33%
1814
11th to 20thDay
18%10%35%445%5%5%6%34%
1800
21st to endDay
24%12%37%5%4445%7%25%
1859
November1st to 10thDay
16%8%46%5%3445%6%40%
1671
11th to 20thDay
18%12%49%5%34345%32%
1710
21st to endDay
19%12%5%7%7%34445%29%
1530
December1st to 10thDay
20%14%5%11%6%445%46%22%
1520
11th to 20thDay
22%11%7%9%5%33345%27%
1906
21st to endDay
20%16%9%10%7%35%445%17%
2772
January1st to 10thNight
15%10%6%9%6%45%5%5%7%27%
2649
11th to 20thNight
18%12%5%9%7%45%5%6%6%24%
2541
21st to endNight
12%10%7%9%8%45%6%6%7%27%
2624
February1st to 10thNight
17%11%5%8%7%46%46%6%25%
2340
11th to 20thNight
14%10%49%9%5%5%5%7%7%25%
2160
21st to endNight
18%10%49%7%35%446%29%
1776
March1st to 10thNight
16%9%48%6%25%5%6%7%32%
2150
11th to 20thNight
15%9%49%8%3435%7%32%
2011
21st to endNight
16%10%46%6%345%5%6%35%
2034
April1st to 10thNight
18%12%47%5%35%5%5%7%29%
1800
11th to 20thNight
18%9%46%6%24447%35%
1775
21st to endNight
20%9%46%5%2445%6%35%
1796
May1st to 10thNight
22%10%47%5%34347%31%
1553
11th to 20thNight
17%7%35%6%345%6%7%37%
1415
21st to endNight
17%6%25%5%345%7%8%38%
1550
June1st to 10thNight
17%6%26%5%3436%8%39%
1440
11th to 20thNight
18%6%345%2445%8%41%
1440
21st to endNight
13%4245%35%5%7%9%43%
1440
July1st to 10thNight
15%435%5%245%6%9%42%
1440
11th to 20thNight
14%5%34435%6%7%10%40%
1440
21st to endNight
12%6%25%5%45%5%6%8%41%
1574
August1st to 10thNight
14%5%25%6%245%7%8%41%
1542
11th to 20thNight
14%7%46%6%35%6%6%7%36%
1726
21st to endNight
17%6%25%43445%8%43%
1980
September1st to 10thNight
18%6%25%425%45%7%43%
1800
11th to 20thNight
16%5%25%434347%49%
1840
21st to endNight
18%7%25%6%3445%7%40%
1980
October1st to 10thNight
22%8%36%5%2435%5%37%
2142
11th to 20thNight
20%9%26%5%24445%38%
2160
21st to endNight
23%11%36%6%2445%6%29%
2496
November1st to 10thNight
14%8%36%5%35%45%6%41%
2407
11th to 20thNight
21%8%37%5%345%5%6%33%
2470
21st to endNight
16%10%47%6%345%6%7%31%
2648
December1st to 10thNight
21%14%6%8%6%345%5%7%21%
2660
11th to 20thNight
20%13%5%10%6%34445%25%
3288
21st to endNight
23%14%6%9%6%34446%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
54%6%13%17%7%1
1518
11th to 20thDay
60%6%13%11%6%3
1448
21st to endDay
54%5%13%17%10%1
1729
February1st to 10thDay
60%7%13%13%7%
1620
11th to 20thDay
53%5%11%18%12%1
1694
21st to endDay
57%5%11%16%9%1
1480
March1st to 10thDay
51%5%15%16%10%2
1800
11th to 20thDay
54%6%9%18%11%2
1944
21st to endDay
54%49%15%15%4
2322
April1st to 10thDay
53%6%8%20%10%3
2160
11th to 20thDay
49%6%11%20%12%2
2134
21st to endDay
53%5%10%18%11%4
2164
May1st to 10thDay
55%6%8%19%10%2
2421
11th to 20thDay
49%6%9%21%12%2
2482
21st to endDay
45%10%14%19%10%2
2725
June1st to 10thDay
48%8%14%18%12%
2520
11th to 20thDay
49%8%13%20%9%1
2520
21st to endDay
46%7%13%23%9%
2520
July1st to 10thDay
44%9%13%21%12%1
2450
11th to 20thDay
39%10%16%23%11%
2445
21st to endDay
44%8%14%19%13%2
2591
August1st to 10thDay
43%8%15%22%11%1
2379
11th to 20thDay
46%10%14%22%7%
2156
21st to endDay
42%8%13%22%13%1
2376
September1st to 10thDay
46%6%12%23%12%1
2160
11th to 20thDay
39%6%11%22%20%1
2120
21st to endDay
45%6%12%20%15%2
1980
October1st to 10thDay
50%7%11%19%12%2
1814
11th to 20thDay
46%7%13%21%11%1
1800
21st to endDay
58%5%13%14%8%2
1859
November1st to 10thDay
42%6%16%19%15%2
1671
11th to 20thDay
54%412%16%11%2
1710
21st to endDay
55%5%15%18%6%1
1530
December1st to 10thDay
62%6%13%11%7%1
1520
11th to 20thDay
57%5%15%16%5%1
1906
21st to endDay
68%6%9%12%6%
2772
January1st to 10thNight
50%6%16%17%10%2
2649
11th to 20thNight
56%7%15%13%7%1
2541
21st to endNight
51%6%15%17%10%2
2624
February1st to 10thNight
55%7%16%14%8%1
2340
11th to 20thNight
53%6%14%17%9%1
2162
21st to endNight
53%5%12%19%9%2
1776
March1st to 10thNight
46%7%16%20%10%2
2160
11th to 20thNight
48%5%15%19%11%2
2012
21st to endNight
46%6%12%18%15%3
2034
April1st to 10thNight
53%6%9%19%11%2
1800
11th to 20thNight
48%6%11%19%16%
1775
21st to endNight
48%7%10%19%13%3
1796
May1st to 10thNight
54%6%9%18%12%2
1553
11th to 20thNight
45%6%11%22%14%2
1416
21st to endNight
41%9%15%24%10%1
1551
June1st to 10thNight
43%6%13%24%14%1
1440
11th to 20thNight
41%8%16%24%11%1
1440
21st to endNight
33%10%17%25%13%
1440
July1st to 10thNight
38%7%15%23%14%2
1400
11th to 20thNight
38%8%16%27%10%1
1392
21st to endNight
37%9%17%21%14%2
1486
August1st to 10thNight
38%9%16%26%10%1
1532
11th to 20thNight
43%9%17%22%10%
1726
21st to endNight
39%7%13%25%15%1
1980
September1st to 10thNight
40%8%14%25%13%1
1800
11th to 20thNight
36%6%10%24%23%1
1840
21st to endNight
43%5%11%22%18%1
1980
October1st to 10thNight
47%7%12%19%14%1
2142
11th to 20thNight
45%6%14%23%10%2
2160
21st to endNight
54%6%12%18%9%1
2496
November1st to 10thNight
42%6%12%20%17%2
2407
11th to 20thNight
48%6%13%18%11%3
2470
21st to endNight
48%6%18%20%7%
2648
December1st to 10thNight
58%8%14%15%5%
2660
11th to 20thNight
57%6%14%15%8%
3288
21st to endNight
61%7%13%13%6%
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
34%24%28%12%11
180
11th to 20thDay
41%26%24%7%2
162
21st to endDay
28%29%31%7%4
241
February1st to 10thDay
36%34%25%5%
240
11th to 20thDay
37%31%24%7%1
353
21st to endDay
40%23%26%10%2
346
March1st to 10thDay
33%22%29%14%2
420
11th to 20thDay
32%27%26%12%31
420
21st to endDay
34%26%23%10%5%2
462
April1st to 10thDay
36%23%25%11%5%1
420
11th to 20thDay
31%22%25%13%7%3
412
21st to endDay
32%19%31%10%5%2
420
May1st to 10thDay
38%18%26%11%43
423
11th to 20thDay
23%20%32%17%5%3
447
21st to endDay
22%11%27%24%12%3
485
June1st to 10thDay
21%15%32%19%10%3
450
11th to 20thDay
23%16%25%23%11%2
450
21st to endDay
18%15%33%21%11%2
450
July1st to 10thDay
14%10%29%27%16%4
445
11th to 20thDay
14%7%30%30%16%3
444
21st to endDay
16%11%35%23%12%3
488
August1st to 10thDay
14%12%26%25%17%6%
446
11th to 20thDay
18%8%25%26%18%6%
439
21st to endDay
17%10%28%22%15%7%
495
September1st to 10thDay
24%10%22%21%15%7%
450
11th to 20thDay
15%14%25%22%14%10%
450
21st to endDay
23%13%28%20%13%4
450
October1st to 10thDay
30%12%23%17%14%4
450
11th to 20thDay
24%19%26%22%8%1
450
21st to endDay
34%17%26%16%6%
435
November1st to 10thDay
27%19%22%20%10%2
365
11th to 20thDay
31%24%24%17%41
370
21st to endDay
31%24%31%12%2
190
December1st to 10thDay
34%26%24%10%5%1
180
11th to 20thDay
41%21%28%8%2
180
21st to endDay
35%29%24%10%21
198
January1st to 10thNight
27%27%30%14%2
760
11th to 20thNight
29%22%27%19%3
727
21st to endNight
21%26%34%16%3
792
February1st to 10thNight
30%22%32%14%1
720
11th to 20thNight
27%29%30%13%1
703
21st to endNight
35%23%24%15%2
592
March1st to 10thNight
29%22%31%14%3
720
11th to 20thNight
25%26%27%18%3
720
21st to endNight
24%24%30%15%6%1
792
April1st to 10thNight
29%22%29%16%4
720
11th to 20thNight
23%21%29%21%6%
711
21st to endNight
28%20%25%20%7%
716
May1st to 10thNight
30%15%23%25%7%1
473
11th to 20thNight
21%12%30%29%7%
354
21st to endNight
20%8%21%34%15%1
389
June1st to 10thNight
19%8%25%33%15%1
360
11th to 20thNight
21%8%22%33%16%1
360
21st to endNight
13%425%43%15%
360
July1st to 10thNight
15%7%19%39%19%2
350
11th to 20thNight
15%322%39%19%2
348
21st to endNight
15%6%21%40%17%1
394
August1st to 10thNight
14%322%35%24%2
468
11th to 20thNight
16%6%16%37%20%4
662
21st to endNight
19%5%17%34%24%2
792
September1st to 10thNight
20%7%24%28%19%3
720
11th to 20thNight
19%8%22%26%19%6%
720
21st to endNight
20%12%21%30%15%3
720
October1st to 10thNight
27%13%21%21%16%2
720
11th to 20thNight
25%13%26%28%8%
720
21st to endNight
29%19%27%19%5%
792
November1st to 10thNight
20%21%26%25%8%1
740
11th to 20thNight
28%21%21%22%7%1
760
21st to endNight
23%22%29%20%5%1
760
December1st to 10thNight
31%26%24%16%4
760
11th to 20thNight
31%24%26%17%3
760
21st to endNight
31%25%26%15%2
836
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