Mount Airy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mount Airy clear sky chart from 2005-11-06 to 2024-01-14.

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
44%
24262
21%
74396
13%
24213
53%
24213
26%
46778

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
27%
758
25%
2459
10%
757
45%
757
24%
1448
January11th to 20thNight
28%
736
23%
2391
11%
736
43%
736
20%
1523
January21st to endNight
27%
792
26%
2574
10%
792
47%
792
24%
1537
February1st to 10thNight
30%
720
21%
2340
11%
720
43%
720
23%
1462
February11th to 20thNight
21%
700
21%
2174
7%
699
37%
699
20%
1397
February21st to endNight
25%
592
24%
1727
11%
592
39%
592
23%
1133
March1st to 10thNight
32%
720
27%
1980
13%
720
45%
720
30%
1208
March11th to 20thNight
29%
720
21%
1980
8%
720
40%
720
23%
1326
March21st to endNight
31%
792
18%
2178
9%
792
39%
792
24%
1466
April1st to 10thNight
34%
720
21%
1951
8%
720
44%
720
28%
1234
April11th to 20thNight
37%
711
23%
1775
9%
711
46%
711
32%
1144
April21st to endNight
41%
590
24%
1670
12%
590
49%
590
29%
1066
May1st to 10thNight
44%
540
17%
1620
8%
540
50%
540
27%
1016
May11th to 20thNight
47%
531
15%
1592
10%
531
50%
531
22%
1096
May21st to endNight
59%
582
14%
1745
12%
582
61%
582
25%
1178
June1st to 10thNight
63%
540
17%
1620
15%
540
65%
540
28%
1041
June11th to 20thNight
62%
540
15%
1620
13%
540
65%
540
31%
1018
June21st to endNight
68%
540
17%
1620
14%
540
70%
540
31%
1028
July1st to 10thNight
68%
525
13%
1575
12%
525
68%
525
26%
1047
July11th to 20thNight
74%
522
14%
1566
14%
522
74%
522
28%
1008
July21st to endNight
71%
591
15%
1672
13%
558
72%
558
28%
1073
August1st to 10thNight
62%
537
13%
1600
10%
534
63%
534
22%
1117
August11th to 20thNight
64%
534
18%
1598
15%
534
65%
534
24%
1093
August21st to endNight
65%
731
17%
1919
13%
731
66%
731
29%
1306
September1st to 10thNight
67%
720
22%
1891
16%
720
69%
720
32%
1238
September11th to 20thNight
54%
720
20%
1980
17%
720
56%
720
27%
1337
September21st to endNight
45%
720
20%
1980
13%
720
51%
720
25%
1367
October1st to 10thNight
50%
720
22%
2114
19%
720
57%
720
30%
1307
October11th to 20thNight
49%
720
29%
2160
22%
720
60%
720
32%
1269
October21st to endNight
50%
792
31%
2376
23%
792
62%
792
33%
1369
November1st to 10thNight
45%
740
28%
2221
20%
740
56%
740
31%
1316
November11th to 20thNight
42%
760
29%
2441
19%
760
57%
760
33%
1344
November21st to endNight
40%
760
27%
2470
17%
760
54%
760
30%
1421
December1st to 10thNight
31%
760
24%
2470
12%
760
47%
760
22%
1582
December11th to 20thNight
33%
759
27%
2925
14%
758
48%
758
23%
1648
December21st to endNight
30%
827
15%
4422
11%
817
43%
817
12%
2615

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
14%5%25%5%35%5%6%8%42%
74942
Night
15%5%25%43445%7%44%
74831
TransparencyDay
40%7%12%21%16%4
74664
Night
39%6%11%21%18%4
74628
SeeingDay
18%11%22%24%17%8%
14129
Night
17%8%23%30%18%3
24279

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
19%6%2442335%6%46%
1706
11th to 20thDay
18%6%25%6%3345%6%44%
1647
21st to endDay
16%5%3442335%5%49%
1782
February1st to 10thDay
14%7%246%445%5%7%43%
1620
11th to 20thDay
21%6%23335%346%43%
1669
21st to endDay
20%6%25%43336%5%41%
1529
March1st to 10thDay
16%42432345%7%49%
1980
11th to 20thDay
20%425%4345%6%7%39%
1980
21st to endDay
19%7%35%5%2445%6%40%
2178
April1st to 10thDay
11%41343447%9%51%
2007
11th to 20thDay
16%4245%3445%8%46%
2134
21st to endDay
15%5%25%435%5%6%6%42%
2304
May1st to 10thDay
13%5%245%46%5%8%8%40%
2340
11th to 20thDay
16%5%36%6%36%5%7%9%35%
2301
21st to endDay
14%5%25%5%36%5%7%9%39%
2531
June1st to 10thDay
10%6%26%5%46%6%7%10%38%
2340
11th to 20thDay
10%425%6%46%8%7%10%39%
2340
21st to endDay
8%425%5%5%7%7%9%11%38%
2340
July1st to 10thDay
10%5%35%6%47%6%9%11%34%
2340
11th to 20thDay
8%426%7%47%9%8%11%33%
2340
21st to endDay
9%5%37%7%5%8%7%8%10%32%
2547
August1st to 10thDay
14%5%36%6%36%7%7%11%32%
2327
11th to 20thDay
11%5%36%7%5%6%8%8%10%33%
2303
21st to endDay
9%5%25%6%36%7%7%11%39%
2417
September1st to 10thDay
12%5%25%5%35%5%6%9%44%
2065
11th to 20thDay
14%5%26%5%35%46%7%43%
1980
21st to endDay
20%7%26%435%45%6%38%
1980
October1st to 10thDay
15%5%145%23435%52%
1845
11th to 20thDay
16%5%23323336%54%
1800
21st to endDay
15%424423236%54%
1980
November1st to 10thDay
13%414322345%57%
1857
11th to 20thDay
15%324324446%54%
1736
21st to endDay
15%42443345%6%51%
1710
December1st to 10thDay
20%8%245%335%5%6%39%
1710
11th to 20thDay
16%422323347%54%
2153
21st to endDay
22%6%244345%5%7%39%
3124
January1st to 10thNight
18%5%24323446%50%
2459
11th to 20thNight
17%6%35%42445%6%44%
2391
21st to endNight
15%5%34433346%49%
2574
February1st to 10thNight
16%6%244245%5%5%44%
2340
11th to 20thNight
21%5%2432335%6%43%
2174
21st to endNight
17%7%26%5%34447%42%
1727
March1st to 10thNight
14%5%2333345%6%52%
1980
11th to 20thNight
17%6%25%4345%6%7%41%
1980
21st to endNight
17%6%35%4345%5%6%42%
2178
April1st to 10thNight
14%5%345%34447%47%
1951
11th to 20thNight
14%5%24435%45%8%47%
1775
21st to endNight
15%42343445%7%47%
1670
May1st to 10thNight
12%6%25%5%35%5%5%8%45%
1620
11th to 20thNight
15%7%36%6%4446%7%38%
1592
21st to endNight
15%6%35%5%3447%10%39%
1744
June1st to 10thNight
11%425%6%35%6%7%10%42%
1620
11th to 20thNight
13%5%24435%37%10%45%
1620
21st to endNight
8%5%25%6%45%6%7%11%42%
1620
July1st to 10thNight
9%7%25%5%45%5%8%9%39%
1620
11th to 20thNight
7%4245%47%8%8%13%39%
1620
21st to endNight
6%5%35%6%47%8%8%13%36%
1771
August1st to 10thNight
14%6%36%6%45%6%7%10%34%
1611
11th to 20thNight
12%6%36%6%45%5%7%9%37%
1598
21st to endNight
10%436%6%46%6%7%10%39%
1919
September1st to 10thNight
10%5%146%35%6%6%9%45%
1891
11th to 20thNight
16%6%37%6%345%5%7%40%
1980
21st to endNight
18%7%36%5%3445%5%39%
1980
October1st to 10thNight
15%6%245%2345%7%47%
2114
11th to 20thNight
14%5%13433445%53%
2160
21st to endNight
15%324423335%55%
2376
November1st to 10thNight
16%5%24423335%54%
2221
11th to 20thNight
15%41332345%6%55%
2441
21st to endNight
15%4233235%5%7%50%
2470
December1st to 10thNight
19%6%25%43445%6%42%
2470
11th to 20thNight
18%424323346%50%
3042
21st to endNight
24%6%244245%5%7%37%
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
40%49%22%20%5%
1707
11th to 20thDay
43%47%22%20%4
1647
21st to endDay
38%38%25%20%6%
1782
February1st to 10thDay
42%412%21%18%4
1620
11th to 20thDay
43%48%21%19%5%
1678
21st to endDay
45%6%11%15%16%7%
1529
March1st to 10thDay
35%5%8%24%22%6%
1980
11th to 20thDay
43%7%9%19%16%6%
1980
21st to endDay
46%49%23%14%4
2178
April1st to 10thDay
30%6%13%24%20%7%
2007
11th to 20thDay
37%5%11%20%20%7%
2134
21st to endDay
41%7%10%24%15%4
2304
May1st to 10thDay
39%8%17%18%14%3
2340
11th to 20thDay
44%9%14%21%9%2
2305
21st to endDay
40%9%16%25%9%1
2531
June1st to 10thDay
40%9%15%24%11%1
2340
11th to 20thDay
38%11%16%18%15%2
2340
21st to endDay
37%10%18%20%13%1
2340
July1st to 10thDay
41%12%16%18%11%3
2275
11th to 20thDay
41%11%18%18%10%1
2271
21st to endDay
43%11%17%18%9%1
2405
August1st to 10thDay
43%11%16%21%8%1
2314
11th to 20thDay
42%12%17%18%9%1
2303
21st to endDay
38%10%18%22%9%3
2417
September1st to 10thDay
36%9%13%21%17%4
2065
11th to 20thDay
41%7%11%22%17%2
1980
21st to endDay
46%5%10%19%17%3
1980
October1st to 10thDay
35%411%23%22%5%
1845
11th to 20thDay
33%48%26%22%7%
1800
21st to endDay
34%37%27%21%8%
1980
November1st to 10thDay
31%39%24%26%8%
1857
11th to 20thDay
33%48%21%26%7%
1736
21st to endDay
35%48%22%26%4
1710
December1st to 10thDay
46%5%7%19%18%4
1710
11th to 20thDay
32%39%22%25%8%
2150
21st to endDay
44%5%10%22%16%3
3124
January1st to 10thNight
37%310%20%21%7%
2459
11th to 20thNight
42%6%9%18%19%5%
2391
21st to endNight
39%37%24%23%4
2574
February1st to 10thNight
41%49%23%18%4
2340
11th to 20thNight
44%48%19%18%7%
2176
21st to endNight
43%411%19%17%6%
1727
March1st to 10thNight
35%47%23%24%7%
1980
11th to 20thNight
43%5%9%23%17%3
1980
21st to endNight
43%5%9%21%18%4
2178
April1st to 10thNight
37%5%11%21%22%5%
1951
11th to 20thNight
36%411%20%20%7%
1775
21st to endNight
37%7%10%25%18%4
1670
May1st to 10thNight
38%6%15%24%15%2
1620
11th to 20thNight
44%8%13%20%13%1
1593
21st to endNight
41%9%16%24%9%1
1745
June1st to 10thNight
36%10%15%25%13%2
1620
11th to 20thNight
35%8%19%23%13%2
1620
21st to endNight
35%8%18%20%13%4
1620
July1st to 10thNight
38%11%16%19%12%4
1575
11th to 20thNight
34%11%22%20%10%3
1566
21st to endNight
35%11%21%23%10%1
1672
August1st to 10thNight
45%9%17%18%10%1
1600
11th to 20thNight
43%9%17%20%10%2
1598
21st to endNight
39%9%17%22%10%2
1919
September1st to 10thNight
35%9%14%20%16%5%
1891
11th to 20thNight
43%6%11%19%19%1
1980
21st to endNight
46%5%10%19%17%3
1980
October1st to 10thNight
37%5%10%21%23%3
2114
11th to 20thNight
34%5%8%26%21%6%
2160
21st to endNight
33%47%22%25%10%
2376
November1st to 10thNight
36%37%21%24%9%
2221
11th to 20thNight
32%39%22%26%9%
2441
21st to endNight
34%48%25%24%6%
2470
December1st to 10thNight
44%47%21%19%4
2470
11th to 20thNight
36%49%19%24%9%
3044
21st to endNight
44%412%20%18%2
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
28%26%32%10%4
270
11th to 20thDay
28%22%33%14%3
249
21st to endDay
26%25%35%12%2
264
February1st to 10thDay
26%23%33%15%3
240
11th to 20thDay
41%19%33%7%1
240
21st to endDay
29%24%31%14%2
247
March1st to 10thDay
22%19%34%20%6%
420
11th to 20thDay
21%23%31%18%5%1
420
21st to endDay
25%18%29%22%6%
462
April1st to 10thDay
18%20%29%20%12%1
420
11th to 20thDay
18%18%24%23%14%3
412
21st to endDay
22%12%30%19%13%4
420
May1st to 10thDay
17%16%28%22%12%5%
423
11th to 20thDay
18%8%25%26%17%7%
447
21st to endDay
19%417%27%23%10%
485
June1st to 10thDay
14%417%33%20%11%
450
11th to 20thDay
13%6%16%28%22%16%
450
21st to endDay
12%5%16%34%23%10%
450
July1st to 10thDay
11%212%25%31%18%
445
11th to 20thDay
7%211%28%32%20%
444
21st to endDay
11%210%27%31%18%
488
August1st to 10thDay
17%313%25%24%18%
446
11th to 20thDay
10%312%27%27%20%
439
21st to endDay
10%49%26%31%20%
495
September1st to 10thDay
15%310%26%29%18%
450
11th to 20thDay
16%411%27%27%15%
450
21st to endDay
20%8%20%27%19%6%
450
October1st to 10thDay
18%6%17%28%24%6%
450
11th to 20thDay
16%10%22%29%19%3
450
21st to endDay
18%12%22%33%11%3
495
November1st to 10thDay
18%11%27%26%14%3
455
11th to 20thDay
19%20%28%21%11%1
296
21st to endDay
16%19%31%24%8%2
270
December1st to 10thDay
27%19%36%14%31
270
11th to 20thDay
21%19%30%21%9%
270
21st to endDay
30%15%28%20%6%1
297
January1st to 10thNight
21%15%32%26%5%
760
11th to 20thNight
20%14%32%29%4
736
21st to endNight
19%11%38%29%3
792
February1st to 10thNight
19%13%33%31%3
720
11th to 20thNight
25%15%34%24%2
703
21st to endNight
19%15%36%28%3
592
March1st to 10thNight
18%13%33%31%5%
720
11th to 20thNight
22%13%31%25%7%2
720
21st to endNight
20%13%31%31%6%
792
April1st to 10thNight
18%14%30%30%8%
720
11th to 20thNight
18%12%28%29%13%1
711
21st to endNight
18%8%28%33%12%1
590
May1st to 10thNight
15%6%27%34%16%1
540
11th to 20thNight
18%6%20%33%21%2
531
21st to endNight
17%210%31%34%6%
584
June1st to 10thNight
11%412%36%33%4
540
11th to 20thNight
15%213%28%36%7%
540
21st to endNight
9%19%35%39%6%
540
July1st to 10thNight
12%26%28%46%7%
525
11th to 20thNight
7%2430%48%9%
522
21st to endNight
8%27%32%43%8%
591
August1st to 10thNight
17%26%30%39%6%
537
11th to 20thNight
14%28%29%38%9%
534
21st to endNight
11%28%27%43%10%
731
September1st to 10thNight
11%310%29%38%10%
720
11th to 20thNight
19%411%27%32%7%
720
21st to endNight
20%5%19%30%24%2
720
October1st to 10thNight
16%7%20%26%26%5%
720
11th to 20thNight
16%6%24%34%18%3
720
21st to endNight
16%10%19%39%15%2
792
November1st to 10thNight
18%9%23%33%16%2
740
11th to 20thNight
18%10%26%36%10%1
760
21st to endNight
17%10%28%32%11%2
760
December1st to 10thNight
24%10%29%30%7%1
760
11th to 20thNight
20%9%33%32%7%
760
21st to endNight
29%10%24%32%5%
836
Page generated at 2024-01-11 13:31:59. Version ac07

Copyright 2024 Attilla Danko


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