Arcadia
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Arcadia clear sky chart from 2005-11-06 to 2024-01-10.

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
42%
24359
24%
74789
15%
24298
51%
24298
31%
44778

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
30%
950
24%
2458
8%
946
41%
946
33%
1544
January11th to 20thNight
26%
900
25%
2340
8%
900
37%
900
31%
1510
January21st to endNight
28%
990
26%
2574
9%
990
39%
990
31%
1626
February1st to 10thNight
23%
900
19%
2340
6%
900
31%
900
27%
1584
February11th to 20thNight
23%
879
19%
2274
6%
875
31%
875
27%
1498
February21st to endNight
24%
511
26%
1695
10%
511
40%
511
23%
1041
March1st to 10thNight
30%
540
24%
1980
13%
540
43%
540
25%
1130
March11th to 20thNight
31%
540
20%
1980
13%
540
41%
540
20%
1235
March21st to endNight
24%
594
17%
2178
9%
594
37%
594
17%
1425
April1st to 10thNight
32%
540
22%
1890
13%
540
46%
540
27%
1072
April11th to 20thNight
33%
533
24%
1775
16%
533
46%
533
25%
1072
April21st to endNight
30%
540
20%
1715
12%
540
43%
540
24%
1094
May1st to 10thNight
37%
540
18%
1620
13%
540
46%
540
24%
1068
May11th to 20thNight
46%
531
21%
1594
18%
531
52%
531
30%
990
May21st to endNight
50%
583
18%
1746
14%
582
57%
582
27%
1112
June1st to 10thNight
66%
540
20%
1580
15%
540
70%
540
39%
884
June11th to 20thNight
64%
540
24%
1484
18%
540
68%
540
43%
833
June21st to endNight
64%
540
24%
1620
19%
540
68%
540
47%
828
July1st to 10thNight
72%
525
19%
1575
18%
525
73%
525
38%
895
July11th to 20thNight
78%
522
23%
1566
23%
522
81%
522
48%
806
July21st to endNight
72%
591
25%
1673
27%
558
74%
558
41%
924
August1st to 10thNight
69%
537
23%
1601
25%
534
72%
534
41%
884
August11th to 20thNight
73%
534
30%
1600
35%
534
76%
534
44%
851
August21st to endNight
76%
594
28%
1952
34%
594
78%
594
42%
983
September1st to 10thNight
67%
540
27%
1800
29%
540
70%
540
37%
970
September11th to 20thNight
63%
540
29%
1968
30%
540
69%
540
32%
1062
September21st to endNight
62%
540
31%
1980
30%
540
68%
540
37%
991
October1st to 10thNight
56%
710
30%
2150
22%
710
62%
710
42%
1145
October11th to 20thNight
36%
720
30%
2160
15%
720
47%
720
37%
1212
October21st to endNight
37%
792
27%
2376
15%
792
46%
792
31%
1416
November1st to 10thNight
38%
740
33%
2220
15%
740
54%
740
41%
1184
November11th to 20thNight
33%
893
28%
2413
11%
893
46%
893
35%
1463
November21st to endNight
31%
950
25%
2636
10%
950
42%
950
32%
1612
December1st to 10thNight
30%
950
22%
2660
8%
950
41%
950
30%
1674
December11th to 20thNight
28%
949
23%
3140
9%
948
38%
948
23%
1960
December21st to endNight
25%
1041
15%
4476
8%
1026
37%
1026
15%
3200

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%6%35%5%3445%7%45%
74442
Night
12%6%35%42445%7%49%
75207
TransparencyDay
39%6%12%25%16%3
74165
Night
35%5%11%26%19%4
75004
SeeingDay
14%9%26%28%19%5%
14401
Night
14%8%31%32%13%1
24365

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
14%7%35%5%23447%48%
1698
11th to 20thDay
14%10%45%434346%43%
1620
21st to endDay
12%9%46%5%34446%44%
1782
February1st to 10thDay
16%10%38%6%2334441%
1620
11th to 20thDay
14%8%5%7%433435%44%
1578
21st to endDay
14%9%37%5%3445%7%39%
1568
March1st to 10thDay
14%8%46%5%24336%44%
1980
11th to 20thDay
22%10%35%42435%5%37%
1980
21st to endDay
20%10%46%5%35%446%33%
2178
April1st to 10thDay
12%7%35%445%5%5%6%44%
2070
11th to 20thDay
16%7%26%5%35%5%5%6%41%
2134
21st to endDay
21%7%36%5%3445%5%37%
2241
May1st to 10thDay
19%8%25%5%4445%6%37%
2340
11th to 20thDay
15%6%36%5%3446%7%40%
2302
21st to endDay
13%6%37%7%35%5%7%10%35%
2531
June1st to 10thDay
6%325%5%35%5%6%10%49%
2360
11th to 20thDay
8%425%5%35%6%6%9%46%
2453
21st to endDay
5%213425%5%6%9%57%
2340
July1st to 10thDay
10%5%26%5%46%6%7%10%40%
2340
11th to 20thDay
43234345%6%10%55%
2340
21st to endDay
8%5%25%5%35%5%8%9%44%
2546
August1st to 10thDay
7%4245%46%6%7%10%45%
2328
11th to 20thDay
9%4245%35%6%5%8%48%
2301
21st to endDay
7%424435%45%8%54%
2403
September1st to 10thDay
11%6%24423347%53%
2160
11th to 20thDay
11%4345%35%5%6%7%48%
1988
21st to endDay
9%42343445%6%56%
1971
October1st to 10thDay
12%5%25%423447%52%
1800
11th to 20thDay
13%5%24323346%55%
1800
21st to endDay
19%6%25%32234448%
1980
November1st to 10thDay
10%5%24423345%59%
1858
11th to 20thDay
14%5%34423445%53%
1763
21st to endDay
15%7%35%423236%51%
1539
December1st to 10thDay
13%8%36%433445%47%
1520
11th to 20thDay
14%9%36%5%23336%44%
1918
21st to endDay
18%16%6%6%5%34446%29%
3112
January1st to 10thNight
12%7%34433446%50%
2458
11th to 20thNight
13%6%35%424446%48%
2340
21st to endNight
11%7%36%433346%49%
2574
February1st to 10thNight
13%11%45%5%2345%5%42%
2340
11th to 20thNight
14%7%45%5%3345%6%45%
2273
21st to endNight
16%9%35%42345%7%44%
1695
March1st to 10thNight
13%6%26%5%24446%48%
1980
11th to 20thNight
18%8%35%434446%44%
1980
21st to endNight
20%7%36%5%3445%7%37%
2178
April1st to 10thNight
10%6%25%42445%7%51%
1890
11th to 20thNight
14%8%34323446%48%
1775
21st to endNight
17%6%35%5%2445%6%43%
1715
May1st to 10thNight
15%6%35%6%35%447%41%
1620
11th to 20thNight
13%5%25%43445%8%48%
1593
21st to endNight
12%5%25%5%35%5%7%9%43%
1745
June1st to 10thNight
5%315%425%5%6%9%54%
1580
11th to 20thNight
4323435%6%7%11%52%
1484
21st to endNight
421342436%8%61%
1620
July1st to 10thNight
7%425%4245%6%10%50%
1620
11th to 20thNight
32133345%6%10%59%
1620
21st to endNight
7%3244245%7%10%51%
1772
August1st to 10thNight
5%3245%25%46%10%53%
1611
11th to 20thNight
6%41442336%8%58%
1600
21st to endNight
5%2245%2435%8%60%
1952
September1st to 10thNight
10%5%24324446%56%
1800
11th to 20thNight
10%4245%2445%8%52%
1968
21st to endNight
7%5%13434447%59%
1980
October1st to 10thNight
9%42332335%7%59%
2150
11th to 20thNight
13%5%24323345%56%
2160
21st to endNight
15%6%24323345%52%
2376
November1st to 10thNight
11%413313335%62%
2220
11th to 20thNight
11%6%25%423345%54%
2413
21st to endNight
16%6%34323336%52%
2636
December1st to 10thNight
13%8%35%42435%7%46%
2660
11th to 20thNight
14%8%35%5%24446%45%
3279
21st to endNight
18%14%5%6%5%33445%33%
4550

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
38%312%27%19%2
1699
11th to 20thDay
43%412%25%15%1
1620
21st to endDay
42%414%26%12%1
1782
February1st to 10thDay
48%410%24%11%2
1620
11th to 20thDay
45%313%21%14%3
1587
21st to endDay
45%48%23%14%6%
1568
March1st to 10thDay
43%310%21%18%5%
1980
11th to 20thDay
50%5%10%20%12%3
1980
21st to endDay
53%6%12%20%8%1
2178
April1st to 10thDay
39%6%12%23%16%2
2070
11th to 20thDay
43%7%13%22%14%2
2134
21st to endDay
49%5%11%23%11%1
2241
May1st to 10thDay
48%6%12%20%12%1
2340
11th to 20thDay
43%6%13%25%12%1
2306
21st to endDay
45%8%16%22%9%
2531
June1st to 10thDay
30%8%17%27%17%2
2360
11th to 20thDay
33%7%13%29%16%2
2453
21st to endDay
22%7%16%33%19%4
2340
July1st to 10thDay
36%8%14%25%14%3
2276
11th to 20thDay
24%7%15%31%19%4
2271
21st to endDay
33%8%15%30%14%1
2405
August1st to 10thDay
31%9%18%25%16%1
2314
11th to 20thDay
32%8%11%29%18%1
2301
21st to endDay
28%7%13%26%20%7%
2403
September1st to 10thDay
33%6%11%28%16%7%
2160
11th to 20thDay
34%6%8%26%23%2
1988
21st to endDay
28%6%10%26%26%5%
1971
October1st to 10thDay
33%5%11%25%22%4
1800
11th to 20thDay
32%37%29%23%6%
1800
21st to endDay
40%49%23%18%6%
1980
November1st to 10thDay
29%49%31%22%5%
1858
11th to 20thDay
35%37%26%24%5%
1763
21st to endDay
38%310%27%21%2
1539
December1st to 10thDay
40%49%32%14%1
1520
11th to 20thDay
43%48%23%18%3
1915
21st to endDay
57%49%19%9%1
3112
January1st to 10thNight
36%412%27%18%3
2458
11th to 20thNight
38%411%29%17%2
2340
21st to endNight
37%314%29%14%3
2574
February1st to 10thNight
44%412%24%14%2
2340
11th to 20thNight
41%410%26%16%3
2274
21st to endNight
42%39%22%17%7%
1695
March1st to 10thNight
38%310%22%21%6%
1980
11th to 20thNight
43%5%10%20%19%3
1980
21st to endNight
47%5%10%23%12%2
2178
April1st to 10thNight
34%6%11%24%22%5%
1890
11th to 20thNight
37%6%9%24%19%4
1775
21st to endNight
42%5%11%23%16%2
1715
May1st to 10thNight
43%6%11%23%16%2
1620
11th to 20thNight
36%7%13%26%16%2
1594
21st to endNight
36%9%16%26%11%1
1746
June1st to 10thNight
25%8%17%29%17%3
1580
11th to 20thNight
25%7%16%30%20%2
1484
21st to endNight
21%5%13%34%22%4
1620
July1st to 10thNight
28%7%15%29%17%4
1575
11th to 20thNight
20%6%11%33%25%4
1566
21st to endNight
26%7%16%31%20%1
1673
August1st to 10thNight
27%6%16%34%14%3
1601
11th to 20thNight
25%5%12%31%26%3
1600
21st to endNight
24%5%13%27%24%7%
1952
September1st to 10thNight
29%5%11%27%21%7%
1800
11th to 20thNight
31%6%8%23%27%6%
1968
21st to endNight
27%5%8%27%28%5%
1980
October1st to 10thNight
25%5%9%26%27%7%
2150
11th to 20thNight
31%38%25%25%7%
2160
21st to endNight
36%48%22%25%6%
2376
November1st to 10thNight
26%410%29%24%7%
2220
11th to 20thNight
34%38%24%27%4
2413
21st to endNight
36%38%25%23%4
2636
December1st to 10thNight
38%413%26%18%1
2660
11th to 20thNight
41%49%24%20%2
3281
21st to endNight
55%49%19%10%2
4550

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
21%13%33%25%7%
267
11th to 20thDay
25%16%38%19%2
240
21st to endDay
14%14%47%18%6%
264
February1st to 10thDay
23%18%35%19%4
240
11th to 20thDay
20%19%40%17%31
240
21st to endDay
24%20%37%16%4
198
March1st to 10thDay
19%20%37%21%3
240
11th to 20thDay
30%13%28%24%6%
240
21st to endDay
29%16%38%13%4
264
April1st to 10thDay
15%17%40%21%7%1
330
11th to 20thDay
17%15%35%25%7%
412
21st to endDay
24%14%31%22%9%1
501
May1st to 10thDay
19%11%35%24%10%1
603
11th to 20thDay
17%11%28%28%13%3
625
21st to endDay
14%8%28%25%19%7%
679
June1st to 10thDay
6%317%33%30%10%
630
11th to 20thDay
9%221%41%21%7%
630
21st to endDay
5%430%35%22%4
630
July1st to 10thDay
10%314%28%32%13%
621
11th to 20thDay
4215%37%34%9%
618
21st to endDay
7%111%34%35%12%
684
August1st to 10thDay
9%212%39%34%5%
626
11th to 20thDay
8%215%33%34%7%
615
21st to endDay
10%29%26%40%12%
522
September1st to 10thDay
12%114%31%32%10%
450
11th to 20thDay
6%214%37%29%13%
278
21st to endDay
13%418%34%23%7%
270
October1st to 10thDay
13%7%26%29%16%9%
270
11th to 20thDay
12%15%40%26%6%1
270
21st to endDay
30%11%31%21%7%1
297
November1st to 10thDay
15%12%36%23%11%3
270
11th to 20thDay
14%17%34%23%10%1
270
21st to endDay
20%17%33%21%8%1
270
December1st to 10thDay
16%11%42%19%9%3
270
11th to 20thDay
16%14%39%24%6%1
270
21st to endDay
21%22%40%16%2
297
January1st to 10thNight
15%13%39%27%6%
950
11th to 20thNight
17%12%41%25%5%
900
21st to endNight
14%13%41%28%4
990
February1st to 10thNight
19%12%42%24%3
900
11th to 20thNight
18%14%40%25%3
879
21st to endNight
22%14%36%24%3
511
March1st to 10thNight
16%11%39%28%6%
540
11th to 20thNight
21%11%33%29%6%
540
21st to endNight
23%12%38%23%41
594
April1st to 10thNight
14%12%38%29%7%
540
11th to 20thNight
19%12%33%30%6%
533
21st to endNight
19%8%39%26%8%
540
May1st to 10thNight
16%6%36%34%9%
540
11th to 20thNight
16%429%35%15%1
531
21st to endNight
12%5%26%35%19%3
584
June1st to 10thNight
6%217%42%31%2
540
11th to 20thNight
6%124%48%21%1
540
21st to endNight
4224%50%19%1
540
July1st to 10thNight
9%111%43%33%3
525
11th to 20thNight
4111%47%34%3
522
21st to endNight
8%111%41%37%2
591
August1st to 10thNight
5%214%43%34%2
537
11th to 20thNight
7%112%48%29%3
534
21st to endNight
5%110%37%43%3
594
September1st to 10thNight
11%214%42%30%2
540
11th to 20thNight
10%317%38%29%4
540
21st to endNight
8%222%43%22%3
540
October1st to 10thNight
9%328%35%21%3
710
11th to 20thNight
14%7%38%32%8%
720
21st to endNight
18%10%32%29%10%1
792
November1st to 10thNight
13%7%39%31%10%1
740
11th to 20thNight
15%12%36%29%8%
893
21st to endNight
20%10%37%27%6%
950
December1st to 10thNight
18%11%38%28%6%
950
11th to 20thNight
21%10%36%30%4
950
21st to endNight
19%14%38%26%3
1045
Page generated at 2024-01-07 09:06:55. Version ac07

Copyright 2024 Attilla Danko


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