Adams Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Adams Observing Site clear sky chart from 2005-11-05 to 2018-01-12.

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
41%
15935
20%
48375
14%
15891
48%
15891
23%
31805

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 15thNight
17%
765
13%
2472
7%
761
25%
761
12%
1869
January16th to endNight
18%
768
17%
2496
8%
768
29%
768
14%
1799
February1st to 15thNight
19%
704
13%
2180
5%
701
29%
701
15%
1575
February16th to endNight
14%
631
14%
1893
5%
631
23%
631
13%
1419
March1st to 15thNight
23%
720
18%
2064
9%
720
31%
720
17%
1459
March16th to endNight
30%
768
15%
2112
8%
768
35%
768
20%
1484
April1st to 15thNight
33%
621
21%
1879
11%
621
43%
621
26%
1181
April16th to endNight
37%
540
22%
1629
9%
540
48%
540
25%
1051
May1st to 15thNight
38%
540
15%
1620
9%
540
43%
540
20%
1125
May16th to endNight
58%
562
19%
1684
14%
561
62%
561
30%
1046
June1st to 15thNight
65%
540
19%
1620
15%
540
69%
540
36%
944
June16th to endNight
63%
540
17%
1620
15%
540
65%
540
34%
962
July1st to 15thNight
58%
510
13%
1530
12%
510
60%
510
28%
977
July16th to endNight
73%
564
20%
1595
18%
531
75%
531
35%
948
August1st to 15thNight
73%
539
23%
1609
20%
536
75%
536
37%
929
August16th to endNight
72%
573
24%
1814
23%
573
74%
573
38%
988
September1st to 15thNight
64%
693
25%
1953
21%
693
66%
693
34%
1197
September16th to endNight
58%
717
29%
1980
23%
717
61%
717
33%
1230
October1st to 15thNight
55%
720
30%
2039
25%
720
61%
720
37%
1190
October16th to endNight
39%
768
27%
2341
20%
768
49%
768
26%
1483
November1st to 15thNight
44%
760
27%
2471
22%
760
54%
760
28%
1473
November16th to endNight
32%
780
24%
2535
16%
780
43%
780
22%
1625
December1st to 15thNight
26%
780
14%
2535
8%
780
34%
780
15%
1818
December16th to endNight
20%
832
15%
2704
7%
832
30%
832
12%
2033

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
16%7%35%5%3445%7%37%
48951
Night
15%7%35%42445%7%40%
48568
Cloud CoverDay
15%7%35%5%3445%7%37%
48961
Night
14%7%35%5%2445%7%39%
48572
TransparencyDay
46%410%21%14%2
48662
Night
44%410%22%15%2
48375
SeeingDay
20%8%22%22%16%9%
5719
Night
20%8%22%27%17%2
15936

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 15thDay
19%10%6%8%6%24345%26%
1710
16th to endDay
19%14%5%5%5%23246%30%
1728
February1st to 15thDay
18%12%49%6%33346%28%
1681
16th to endDay
17%13%46%5%25%446%29%
1580
March1st to 15thDay
23%9%35%42335%433%
1885
16th to endDay
20%7%35%5%2445%6%33%
2112
April1st to 15thDay
19%5%35%5%23436%40%
2079
16th to endDay
17%6%245%345%47%38%
2328
May1st to 15thDay
22%6%26%5%35%5%5%6%30%
2331
16th to endDay
12%5%25%5%45%5%6%9%37%
2431
June1st to 15thDay
10%425%5%35%5%6%8%42%
2340
16th to endDay
10%5%25%6%46%5%6%9%38%
2340
July1st to 15thDay
15%6%246%25%5%7%8%33%
2340
16th to endDay
11%5%25%5%5%6%7%7%10%33%
2465
August1st to 15thDay
10%425%6%45%5%6%10%39%
2340
16th to endDay
9%5%245%45%5%7%9%40%
2386
September1st to 15thDay
13%5%244345%47%44%
1995
16th to endDay
16%425%423345%47%
1980
October1st to 15thDay
13%414333346%50%
1920
16th to endDay
22%5%24213335%45%
1881
November1st to 15thDay
14%6%24433335%48%
1717
16th to endDay
16%9%25%424345%40%
1755
December1st to 15thDay
23%11%36%434245%30%
1755
16th to endDay
22%12%47%423435%28%
1872
January1st to 15thNight
18%12%5%9%6%2434426%
2472
16th to endNight
19%11%5%7%5%2434332%
2496
February1st to 15thNight
20%10%47%424345%32%
2178
16th to endNight
19%11%47%5%35%346%27%
1893
March1st to 15thNight
18%8%35%5%34345%35%
2052
16th to endNight
16%7%36%5%25%45%7%35%
2112
April1st to 15thNight
14%5%3442345%6%44%
1879
16th to endNight
15%6%25%43345%7%42%
1629
May1st to 15thNight
17%6%26%5%35%45%8%33%
1620
16th to endNight
9%5%13435%6%6%9%43%
1682
June1st to 15thNight
5%414325%5%7%10%48%
1620
16th to endNight
7%414335%5%7%11%45%
1620
July1st to 15thNight
11%5%26%445%35%8%42%
1620
16th to endNight
6%3134345%7%10%46%
1703
August1st to 15thNight
5%313425%5%7%10%48%
1620
16th to endNight
6%41342446%10%51%
1814
September1st to 15thNight
12%41432445%8%47%
1953
16th to endNight
10%5%245%33346%49%
1980
October1st to 15thNight
11%413324448%50%
2039
16th to endNight
18%6%24423326%45%
2341
November1st to 15thNight
15%5%14322435%48%
2471
16th to endNight
19%9%23323345%41%
2535
December1st to 15thNight
22%10%35%5%24346%30%
2535
16th to endNight
21%12%45%5%34346%26%
2704

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 15thDay
19%10%5%9%6%24445%26%
1710
16th to endDay
19%14%5%5%5%23346%29%
1728
February1st to 15thDay
18%12%49%6%24345%28%
1681
16th to endDay
17%12%47%5%35%345%29%
1580
March1st to 15thDay
22%9%35%5%2434433%
1896
16th to endDay
20%8%35%5%2445%5%33%
2111
April1st to 15thDay
18%6%35%5%23346%40%
2079
16th to endDay
16%7%25%5%33447%38%
2328
May1st to 15thDay
21%6%36%6%35%5%46%31%
2331
16th to endDay
11%5%35%5%35%6%6%10%36%
2431
June1st to 15thDay
9%5%25%5%35%6%6%8%41%
2340
16th to endDay
10%5%26%6%46%5%6%9%37%
2340
July1st to 15thDay
15%6%25%5%35%6%6%9%33%
2340
16th to endDay
10%5%25%5%47%7%7%9%34%
2465
August1st to 15thDay
10%5%15%6%45%5%6%10%38%
2340
16th to endDay
10%5%245%35%5%7%9%39%
2386
September1st to 15thDay
13%5%24434448%43%
1995
16th to endDay
16%425%323346%46%
1980
October1st to 15thDay
12%5%2442335%6%50%
1920
16th to endDay
21%5%14212335%46%
1881
November1st to 15thDay
13%6%24423335%48%
1717
16th to endDay
16%8%35%433345%41%
1755
December1st to 15thDay
23%11%46%423345%30%
1755
16th to endDay
21%12%5%7%5%22335%28%
1872
January1st to 15thNight
17%13%5%9%7%2435%426%
2472
16th to endNight
18%11%6%6%5%3344432%
2496
February1st to 15thNight
19%10%47%5%24345%32%
2171
16th to endNight
19%12%38%5%34445%27%
1893
March1st to 15thNight
18%8%36%5%34445%34%
2064
16th to endNight
16%7%46%6%25%35%6%35%
2112
April1st to 15thNight
15%6%2442445%7%43%
1879
16th to endNight
14%6%35%43435%7%41%
1629
May1st to 15thNight
18%5%36%5%35%45%7%33%
1619
16th to endNight
9%4145%36%6%6%9%43%
1682
June1st to 15thNight
5%414335%6%6%9%49%
1620
16th to endNight
7%324425%5%7%11%44%
1620
July1st to 15thNight
11%5%26%5%35%45%8%42%
1620
16th to endNight
6%4234445%7%9%46%
1703
August1st to 15thNight
5%314425%5%7%10%48%
1620
16th to endNight
6%31342446%10%51%
1814
September1st to 15thNight
12%41343445%8%47%
1953
16th to endNight
10%5%25%6%23337%49%
1980
October1st to 15thNight
11%31333335%8%51%
2039
16th to endNight
18%5%24423235%45%
2341
November1st to 15thNight
15%5%24423335%49%
2471
16th to endNight
19%8%23323345%41%
2535
December1st to 15thNight
21%10%36%424345%30%
2535
16th to endNight
21%12%46%5%34346%26%
2704

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 15thDay
61%37%16%10%1
1711
16th to endDay
57%29%22%6%1
1728
February1st to 15thDay
58%38%20%8%1
1683
16th to endDay
56%310%20%8%
1580
March1st to 15thDay
54%29%20%11%1
1896
16th to endDay
52%49%22%9%1
2112
April1st to 15thDay
46%37%24%14%3
2079
16th to endDay
45%49%21%13%5%
2328
May1st to 15thDay
53%410%19%9%1
2331
16th to endDay
43%6%14%22%12%1
2435
June1st to 15thDay
38%5%13%24%16%1
2340
16th to endDay
42%5%12%17%18%2
2340
July1st to 15thDay
46%5%13%16%15%2
2201
16th to endDay
42%6%12%22%12%1
2310
August1st to 15thDay
40%5%15%23%14%1
2327
16th to endDay
38%413%24%15%3
2386
September1st to 15thDay
40%311%20%17%5%
1995
16th to endDay
39%28%23%23%2
1980
October1st to 15thDay
35%39%26%22%3
1920
16th to endDay
41%28%27%17%2
1881
November1st to 15thDay
40%27%24%20%4
1717
16th to endDay
46%26%24%18%1
1755
December1st to 15thDay
57%210%18%9%1
1755
16th to endDay
59%310%18%7%
1872
January1st to 15thNight
61%27%14%12%1
2472
16th to endNight
57%27%22%8%1
2496
February1st to 15thNight
55%39%21%9%1
2180
16th to endNight
58%39%18%8%
1893
March1st to 15thNight
52%38%21%12%1
2064
16th to endNight
49%412%21%11%
2112
April1st to 15thNight
39%49%21%22%3
1879
16th to endNight
41%410%22%14%6%
1629
May1st to 15thNight
48%6%12%21%9%3
1620
16th to endNight
36%6%15%22%15%3
1684
June1st to 15thNight
29%6%14%28%17%3
1620
16th to endNight
31%7%15%24%17%4
1620
July1st to 15thNight
41%412%20%16%4
1530
16th to endNight
30%7%15%27%16%3
1595
August1st to 15thNight
29%6%16%25%19%2
1609
16th to endNight
27%5%14%26%20%4
1814
September1st to 15thNight
35%411%21%19%7%
1953
16th to endNight
36%37%22%27%2
1980
October1st to 15thNight
32%310%27%21%5%
2039
16th to endNight
42%26%23%21%2
2341
November1st to 15thNight
38%26%22%23%5%
2471
16th to endNight
45%27%25%17%1
2535
December1st to 15thNight
55%39%19%9%1
2535
16th to endNight
60%39%17%8%1
2704

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 15thDay
29%21%30%12%41
123
16th to endDay
46%21%21%8%1
96
February1st to 15thDay
26%33%30%8%1
90
16th to endDay
32%9%45%12%
81
March1st to 15thDay
35%10%31%18%4
186
16th to endDay
27%12%32%17%8%
288
April1st to 15thDay
25%10%29%22%8%3
270
16th to endDay
18%12%29%21%10%7%
270
May1st to 15thDay
29%10%26%14%11%6%
288
16th to endDay
16%5%25%24%15%12%
331
June1st to 15thDay
10%5%20%33%18%11%
315
16th to endDay
14%7%21%26%16%13%
315
July1st to 15thDay
24%316%24%15%15%
305
16th to endDay
11%113%27%20%25%
326
August1st to 15thDay
12%211%24%29%19%
313
16th to endDay
13%311%29%25%17%
332
September1st to 15thDay
16%312%21%30%15%
315
16th to endDay
17%314%20%30%13%
314
October1st to 15thDay
17%5%18%28%20%9%
315
16th to endDay
20%8%25%26%15%3
297
November1st to 15thDay
21%5%36%20%12%2
135
16th to endDay
26%8%34%18%9%2
135
December1st to 15thDay
34%14%30%12%7%1
135
16th to endDay
34%26%32%6%
144
January1st to 15thNight
29%16%30%18%4
765
16th to endNight
27%18%31%21%1
768
February1st to 15thNight
30%14%31%22%1
704
16th to endNight
29%16%35%17%1
631
March1st to 15thNight
26%13%29%23%5%
720
16th to endNight
22%12%28%25%10%
768
April1st to 15thNight
20%12%29%25%10%
621
16th to endNight
19%8%30%27%12%1
540
May1st to 15thNight
22%6%24%30%14%2
540
16th to endNight
11%219%33%27%6%
563
June1st to 15thNight
6%216%42%27%4
540
16th to endNight
9%118%37%30%3
540
July1st to 15thNight
16%12%31%32%5%
510
16th to endNight
8%17%32%40%8%
564
August1st to 15thNight
7%8%33%43%7%
539
16th to endNight
9%7%35%37%8%
573
September1st to 15thNight
14%110%31%35%6%
693
16th to endNight
14%412%28%35%5%
717
October1st to 15thNight
13%5%20%30%24%6%
720
16th to endNight
22%8%26%24%16%1
768
November1st to 15thNight
19%8%23%27%18%1
760
16th to endNight
25%11%26%25%10%1
780
December1st to 15thNight
30%13%22%26%6%
780
16th to endNight
30%13%30%21%3
832
Page generated at 2018-01-12 22:01:25. Version ac04

Copyright 2018 A. Danko


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