Cary
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cary 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
44%
24569
22%
74781
14%
24519
53%
24519
28%
46479

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%
757
24%
2459
10%
757
44%
757
24%
1492
January11th to 20thNight
29%
744
25%
2417
12%
744
45%
744
23%
1505
January21st to endNight
28%
792
28%
2574
14%
792
48%
792
29%
1506
February1st to 10thNight
27%
720
20%
2340
11%
720
40%
720
25%
1460
February11th to 20thNight
20%
701
20%
2255
7%
699
36%
699
21%
1437
February21st to endNight
26%
592
30%
1643
13%
592
43%
592
28%
1038
March1st to 10thNight
31%
720
27%
1980
14%
720
44%
720
31%
1215
March11th to 20thNight
29%
720
20%
1980
9%
720
40%
720
25%
1321
March21st to endNight
29%
792
21%
2178
9%
792
40%
792
28%
1413
April1st to 10thNight
31%
720
24%
1864
9%
720
42%
720
30%
1191
April11th to 20thNight
37%
711
26%
1775
10%
711
46%
711
35%
1124
April21st to endNight
40%
720
24%
1800
9%
720
47%
720
35%
1153
May1st to 10thNight
39%
589
19%
1669
9%
589
46%
589
32%
1043
May11th to 20thNight
46%
531
17%
1593
9%
531
50%
531
25%
1047
May21st to endNight
63%
582
16%
1744
13%
582
65%
582
30%
1106
June1st to 10thNight
58%
540
16%
1620
14%
540
60%
540
28%
1028
June11th to 20thNight
57%
540
16%
1620
12%
540
60%
540
29%
1034
June21st to endNight
63%
540
16%
1620
13%
540
66%
540
27%
1052
July1st to 10thNight
68%
525
13%
1575
12%
525
69%
525
28%
1040
July11th to 20thNight
72%
522
14%
1566
13%
522
73%
522
28%
1025
July21st to endNight
68%
591
17%
1672
13%
558
70%
558
27%
1079
August1st to 10thNight
66%
537
13%
1600
11%
534
67%
534
24%
1079
August11th to 20thNight
64%
592
16%
1656
13%
592
64%
592
25%
1151
August21st to endNight
64%
792
17%
1980
12%
792
65%
792
30%
1351
September1st to 10thNight
69%
720
24%
1800
17%
720
69%
720
35%
1183
September11th to 20thNight
60%
720
26%
1909
21%
720
63%
720
32%
1233
September21st to endNight
48%
720
18%
2022
14%
720
53%
720
24%
1397
October1st to 10thNight
54%
720
25%
2160
23%
720
61%
720
32%
1309
October11th to 20thNight
48%
720
30%
2160
24%
720
59%
720
33%
1259
October21st to endNight
47%
792
32%
2376
22%
792
62%
792
36%
1340
November1st to 10thNight
48%
740
27%
2221
21%
740
58%
740
34%
1307
November11th to 20thNight
42%
760
29%
2280
19%
760
55%
760
32%
1344
November21st to endNight
43%
760
27%
2583
19%
760
56%
760
31%
1453
December1st to 10thNight
31%
760
21%
2660
12%
760
45%
760
20%
1675
December11th to 20thNight
35%
760
25%
3054
17%
758
48%
758
23%
1749
December21st to endNight
33%
827
18%
4376
14%
817
45%
817
16%
2340

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
13%5%25%5%35%5%6%8%43%
74544
Night
14%5%25%5%3445%7%45%
75250
TransparencyDay
39%5%12%22%18%4
74266
Night
39%5%11%21%20%5%
75047
SeeingDay
16%9%23%25%19%7%
14210
Night
16%7%25%32%17%2
24585

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
16%6%27%424435%46%
1706
11th to 20thDay
18%6%35%32445%5%44%
1665
21st to endDay
17%5%25%424446%47%
1782
February1st to 10thDay
15%7%25%5%445%5%6%43%
1620
11th to 20thDay
22%6%23333345%46%
1591
21st to endDay
20%7%36%33445%5%41%
1610
March1st to 10thDay
15%5%144235%46%51%
1980
11th to 20thDay
15%5%36%5%345%47%43%
1980
21st to endDay
17%7%36%5%3446%6%40%
2178
April1st to 10thDay
11%424324448%54%
2095
11th to 20thDay
11%5%245%35%46%7%48%
2134
21st to endDay
15%5%35%425%5%5%7%45%
2160
May1st to 10thDay
11%6%35%5%35%5%7%9%42%
2305
11th to 20thDay
14%6%36%5%45%5%6%7%39%
2301
21st to endDay
12%6%25%6%35%6%6%9%39%
2531
June1st to 10thDay
10%5%35%5%46%6%7%9%38%
2340
11th to 20thDay
10%5%246%45%6%7%10%41%
2340
21st to endDay
8%426%6%47%7%7%11%38%
2340
July1st to 10thDay
8%426%7%47%8%8%11%33%
2340
11th to 20thDay
8%5%36%7%5%6%7%9%12%32%
2340
21st to endDay
7%436%7%48%8%8%10%35%
2547
August1st to 10thDay
10%6%36%8%46%7%8%10%31%
2327
11th to 20thDay
11%6%37%7%5%6%7%7%9%33%
2227
21st to endDay
11%6%37%6%45%6%8%9%36%
2376
September1st to 10thDay
8%425%6%45%5%6%8%47%
2160
11th to 20thDay
15%5%35%4445%5%8%43%
2047
21st to endDay
20%6%27%43345%7%39%
1936
October1st to 10thDay
15%6%25%423347%49%
1800
11th to 20thDay
13%423323346%57%
1800
21st to endDay
12%425%434336%56%
1980
November1st to 10thDay
13%5%24323345%55%
1857
11th to 20thDay
15%423334347%53%
1900
21st to endDay
14%42442445%6%51%
1586
December1st to 10thDay
18%7%25%42445%7%42%
1520
11th to 20thDay
16%42332235%5%56%
2019
21st to endDay
16%6%25%4345%5%7%42%
3124
January1st to 10thNight
16%6%24434446%46%
2459
11th to 20thNight
16%7%35%5%3445%7%43%
2417
21st to endNight
16%6%24323445%50%
2574
February1st to 10thNight
18%5%245%3445%7%43%
2340
11th to 20thNight
20%6%25%335%445%43%
2255
21st to endNight
18%4245%245%5%7%45%
1643
March1st to 10thNight
14%5%25%42435%453%
1980
11th to 20thNight
17%5%34435%5%5%7%41%
1980
21st to endNight
15%6%345%34447%45%
2178
April1st to 10thNight
14%5%2443445%6%49%
1864
11th to 20thNight
13%5%25%43445%7%49%
1775
21st to endNight
12%3245%346%47%48%
1800
May1st to 10thNight
10%6%35%436%5%6%8%46%
1669
11th to 20thNight
15%6%35%6%35%46%8%40%
1592
21st to endNight
11%5%25%6%445%7%9%42%
1744
June1st to 10thNight
10%5%35%5%36%6%7%9%40%
1620
11th to 20thNight
11%6%35%5%35%5%7%9%40%
1620
21st to endNight
8%5%36%6%35%6%8%12%38%
1620
July1st to 10thNight
5%5%36%7%36%8%9%11%37%
1620
11th to 20thNight
6%5%25%6%48%7%8%12%37%
1620
21st to endNight
7%436%6%47%6%8%12%37%
1771
August1st to 10thNight
9%5%36%7%46%7%9%10%33%
1611
11th to 20thNight
12%5%36%7%46%6%8%11%34%
1656
21st to endNight
10%5%36%6%36%6%7%11%38%
1980
September1st to 10thNight
12%5%25%4245%6%9%47%
1800
11th to 20thNight
12%5%36%5%3445%7%45%
1909
21st to endNight
18%6%36%6%3446%6%37%
2022
October1st to 10thNight
14%5%26%423346%49%
2160
11th to 20thNight
14%6%24424346%52%
2160
21st to endNight
12%5%2442335%5%55%
2376
November1st to 10thNight
13%6%25%323445%53%
2221
11th to 20thNight
13%5%2442445%5%51%
2280
21st to endNight
13%42443445%7%51%
2583
December1st to 10thNight
18%6%35%5%3345%5%42%
2660
11th to 20thNight
17%6%24323345%49%
3159
21st to endNight
17%6%25%423347%47%
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
43%36%22%20%5%
1707
11th to 20thDay
43%37%20%23%4
1665
21st to endDay
39%37%21%23%7%
1782
February1st to 10thDay
41%311%22%18%5%
1620
11th to 20thDay
42%37%19%22%6%
1600
21st to endDay
45%49%16%20%6%
1610
March1st to 10thDay
35%48%22%24%7%
1980
11th to 20thDay
41%49%21%18%7%
1980
21st to endDay
44%5%9%20%18%3
2178
April1st to 10thDay
29%5%9%25%24%8%
2095
11th to 20thDay
35%410%23%21%7%
2134
21st to endDay
39%411%22%19%5%
2160
May1st to 10thDay
37%6%15%21%17%3
2305
11th to 20thDay
44%6%13%22%14%2
2305
21st to endDay
40%6%15%25%14%1
2531
June1st to 10thDay
39%7%15%22%15%1
2340
11th to 20thDay
36%8%16%24%14%2
2340
21st to endDay
38%9%15%22%15%1
2340
July1st to 10thDay
40%9%16%19%12%3
2275
11th to 20thDay
40%8%20%21%9%2
2271
21st to endDay
39%9%19%23%9%1
2405
August1st to 10thDay
44%8%17%21%9%1
2314
11th to 20thDay
45%8%16%20%9%1
2227
21st to endDay
41%7%16%22%11%3
2376
September1st to 10thDay
34%7%15%20%19%5%
2160
11th to 20thDay
39%5%11%20%22%4
2047
21st to endDay
45%5%8%20%17%4
1936
October1st to 10thDay
38%310%23%23%4
1800
11th to 20thDay
31%38%29%22%7%
1800
21st to endDay
33%36%23%26%9%
1980
November1st to 10thDay
33%27%22%28%7%
1857
11th to 20thDay
33%39%21%27%7%
1900
21st to endDay
35%38%24%25%6%
1586
December1st to 10thDay
43%310%22%17%4
1520
11th to 20thDay
32%27%27%24%9%
2016
21st to endDay
43%39%23%21%2
3124
January1st to 10thNight
40%38%20%24%6%
2459
11th to 20thNight
42%410%18%21%5%
2417
21st to endNight
37%35%23%27%6%
2574
February1st to 10thNight
41%48%21%20%6%
2340
11th to 20thNight
44%37%17%21%7%
2257
21st to endNight
39%38%20%21%8%
1643
March1st to 10thNight
36%38%21%23%9%
1980
11th to 20thNight
42%6%8%19%19%6%
1980
21st to endNight
40%410%21%20%5%
2178
April1st to 10thNight
37%48%17%26%8%
1864
11th to 20thNight
35%39%23%22%8%
1775
21st to endNight
35%6%10%26%19%5%
1800
May1st to 10thNight
36%5%15%22%18%4
1669
11th to 20thNight
43%6%12%22%16%1
1593
21st to endNight
37%8%17%23%15%1
1745
June1st to 10thNight
38%8%15%22%16%1
1620
11th to 20thNight
39%7%17%20%16%3
1620
21st to endNight
37%10%16%21%13%3
1620
July1st to 10thNight
38%10%18%19%12%2
1575
11th to 20thNight
36%11%20%21%10%3
1566
21st to endNight
38%8%20%22%11%
1672
August1st to 10thNight
42%9%19%21%8%1
1600
11th to 20thNight
42%9%18%20%8%2
1656
21st to endNight
40%8%17%24%10%2
1980
September1st to 10thNight
35%7%14%22%17%5%
1800
11th to 20thNight
39%5%11%20%22%3
1909
21st to endNight
47%412%16%17%4
2022
October1st to 10thNight
38%39%22%23%5%
2160
11th to 20thNight
35%38%22%25%7%
2160
21st to endNight
32%27%22%26%10%
2376
November1st to 10thNight
35%38%18%28%9%
2221
11th to 20thNight
36%38%17%25%11%
2280
21st to endNight
34%37%22%26%7%
2583
December1st to 10thNight
45%38%20%19%5%
2660
11th to 20thNight
39%37%21%23%8%
3161
21st to endNight
40%26%25%24%3
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
19%24%37%16%4
270
11th to 20thDay
22%25%31%17%4
255
21st to endDay
19%22%39%18%2
264
February1st to 10thDay
21%16%40%18%5%
240
11th to 20thDay
37%14%35%12%2
258
21st to endDay
26%18%31%21%3
346
March1st to 10thDay
20%16%36%21%6%
420
11th to 20thDay
21%18%39%16%6%1
420
21st to endDay
21%15%33%23%6%1
462
April1st to 10thDay
17%17%31%24%9%1
420
11th to 20thDay
13%16%28%23%15%4
412
21st to endDay
19%13%25%26%15%2
420
May1st to 10thDay
16%13%31%22%12%5%
423
11th to 20thDay
15%7%21%30%21%6%
447
21st to endDay
20%416%27%23%10%
485
June1st to 10thDay
12%6%18%32%24%8%
450
11th to 20thDay
11%5%19%25%27%12%
450
21st to endDay
10%5%15%33%28%10%
450
July1st to 10thDay
9%29%31%33%16%
445
11th to 20thDay
6%29%26%40%17%
444
21st to endDay
9%210%35%33%12%
488
August1st to 10thDay
13%314%29%29%13%
446
11th to 20thDay
13%311%24%33%18%
439
21st to endDay
13%39%26%28%21%
495
September1st to 10thDay
11%314%26%29%18%
450
11th to 20thDay
15%410%29%30%12%
450
21st to endDay
23%6%18%28%20%5%
450
October1st to 10thDay
19%5%20%23%24%10%
450
11th to 20thDay
13%7%24%30%21%5%
450
21st to endDay
13%9%24%33%16%4
495
November1st to 10thDay
18%8%27%27%16%3
455
11th to 20thDay
17%11%29%30%11%2
460
21st to endDay
14%15%32%22%14%2
211
December1st to 10thDay
21%15%39%17%9%
180
11th to 20thDay
19%14%35%22%10%1
213
21st to endDay
23%14%32%19%10%1
297
January1st to 10thNight
19%13%35%27%5%
760
11th to 20thNight
18%12%35%29%6%
744
21st to endNight
19%9%40%28%4
792
February1st to 10thNight
20%9%40%28%3
720
11th to 20thNight
23%14%40%22%1
703
21st to endNight
20%13%37%25%5%
592
March1st to 10thNight
16%13%35%31%5%
720
11th to 20thNight
21%9%36%24%8%
720
21st to endNight
18%11%38%28%5%1
792
April1st to 10thNight
17%14%34%28%7%
720
11th to 20thNight
15%11%33%28%12%1
711
21st to endNight
14%6%36%35%9%1
720
May1st to 10thNight
12%10%33%35%9%
589
11th to 20thNight
19%5%22%36%17%1
531
21st to endNight
14%212%43%27%2
584
June1st to 10thNight
11%317%43%25%1
540
11th to 20thNight
13%415%36%27%5%
540
21st to endNight
8%313%41%32%2
540
July1st to 10thNight
8%210%36%41%4
525
11th to 20thNight
8%27%41%36%6%
522
21st to endNight
8%29%40%36%4
591
August1st to 10thNight
11%18%42%34%4
537
11th to 20thNight
14%28%36%35%5%
592
21st to endNight
12%29%31%39%6%
792
September1st to 10thNight
13%28%32%38%6%
720
11th to 20thNight
14%311%34%33%4
720
21st to endNight
23%314%34%23%2
720
October1st to 10thNight
17%318%32%26%5%
720
11th to 20thNight
16%8%23%31%21%2
720
21st to endNight
15%7%25%32%20%2
792
November1st to 10thNight
16%7%24%35%15%3
740
11th to 20thNight
15%10%28%35%11%
760
21st to endNight
14%8%30%33%14%1
760
December1st to 10thNight
20%8%33%31%8%
760
11th to 20thNight
19%8%32%34%8%
760
21st to endNight
20%11%29%31%9%
836
Page generated at 2024-01-13 09:37:57. Version ac07

Copyright 2024 Attilla Danko


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