Range Land
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Range Land clear sky chart from 2005-11-06 to 2024-01-13.

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
66%
23258
28%
74643
26%
23227
71%
23227
42%
38455

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
56%
756
20%
2646
19%
756
62%
756
28%
1520
January11th to 20thNight
60%
732
20%
2562
19%
732
66%
732
31%
1425
January21st to endNight
63%
792
26%
2574
26%
792
68%
792
31%
1511
February1st to 10thNight
62%
720
26%
2338
26%
720
68%
720
37%
1255
February11th to 20thNight
63%
700
27%
2099
24%
700
70%
700
39%
1144
February21st to endNight
58%
592
27%
1776
24%
592
66%
592
39%
975
March1st to 10thNight
54%
720
20%
2160
18%
720
60%
720
33%
1285
March11th to 20thNight
59%
720
24%
2031
21%
720
64%
720
39%
1155
March21st to endNight
52%
792
21%
2026
12%
792
58%
792
41%
1203
April1st to 10thNight
56%
720
26%
1800
14%
720
62%
720
41%
1072
April11th to 20thNight
57%
711
29%
1779
15%
711
61%
711
44%
1007
April21st to endNight
60%
720
25%
1800
13%
720
63%
720
48%
1016
May1st to 10thNight
56%
579
30%
1659
20%
579
61%
579
44%
869
May11th to 20thNight
62%
386
29%
1448
29%
386
68%
386
40%
680
May21st to endNight
64%
388
22%
1552
24%
388
69%
388
33%
758
June1st to 10thNight
66%
360
26%
1440
32%
360
72%
360
37%
667
June11th to 20thNight
70%
360
34%
1440
38%
360
81%
360
57%
522
June21st to endNight
78%
360
33%
1440
42%
360
84%
360
56%
532
July1st to 10thNight
82%
350
34%
1400
43%
350
88%
350
67%
460
July11th to 20thNight
83%
348
37%
1392
45%
348
88%
348
64%
474
July21st to endNight
83%
400
40%
1494
48%
378
86%
378
55%
561
August1st to 10thNight
81%
555
34%
1620
27%
552
84%
552
58%
768
August11th to 20thNight
79%
712
37%
1780
23%
712
81%
712
71%
857
August21st to endNight
80%
792
42%
1980
27%
792
80%
792
77%
914
September1st to 10thNight
83%
720
44%
1800
29%
720
86%
720
78%
824
September11th to 20thNight
78%
720
44%
1837
32%
720
83%
720
69%
879
September21st to endNight
77%
720
41%
1980
36%
720
82%
720
63%
932
October1st to 10thNight
74%
720
34%
2113
30%
720
80%
720
55%
1009
October11th to 20thNight
75%
720
39%
2160
39%
720
81%
720
58%
974
October21st to endNight
73%
792
38%
2448
38%
792
79%
792
57%
1090
November1st to 10thNight
66%
740
30%
2405
29%
740
71%
740
41%
1229
November11th to 20thNight
68%
760
29%
2470
28%
760
74%
760
43%
1227
November21st to endNight
64%
760
30%
2541
28%
760
71%
760
40%
1287
December1st to 10thNight
60%
760
22%
2660
22%
760
64%
760
31%
1457
December11th to 20thNight
57%
759
19%
3203
19%
758
63%
758
20%
2047
December21st to endNight
48%
822
13%
4790
17%
817
55%
817
14%
2870

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
342442445%7%60%
74788
Night
342443446%8%58%
74972
TransparencyDay
22%5%9%21%24%19%
74493
Night
24%5%11%24%22%14%
74788
SeeingDay
6%11%22%30%23%8%
13838
Night
5%5%17%43%27%4
23282

By Month

Percentage Cloud Cover SW (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
36%27%6%45%6%8%14%37%
1519
11th to 20thDay
35%36%6%35%6%7%9%47%
1459
21st to endDay
5%7%36%5%38%7%8%12%37%
1781
February1st to 10thDay
5%426%5%35%6%7%10%47%
1620
11th to 20thDay
35%36%6%36%5%6%10%48%
1750
21st to endDay
35%36%4346%8%9%49%
1480
March1st to 10thDay
46%45%5%46%6%7%9%44%
1800
11th to 20thDay
35%37%5%46%6%6%10%44%
1926
21st to endDay
35%25%6%35%5%7%9%49%
2330
April1st to 10thDay
35%36%5%346%6%9%50%
2160
11th to 20thDay
3435%5%345%5%8%56%
2129
21st to endDay
5%5%2432345%7%60%
2160
May1st to 10thDay
342342335%8%62%
2299
11th to 20thDay
5%42443445%8%58%
2441
21st to endDay
6%6%35%5%345%5%8%51%
2723
June1st to 10thDay
342342445%8%61%
2520
11th to 20thDay
2213222336%74%
2520
21st to endDay
321322233477%
2520
July1st to 10thDay
1112213345%79%
2520
11th to 20thDay
111121224480%
2520
21st to endDay
2212323446%71%
2732
August1st to 10thDay
3212323445%71%
2307
11th to 20thDay
21121333480%
2122
21st to endDay
11111223483%
2376
September1st to 10thDay
11111123483%
2160
11th to 20thDay
2112312236%76%
2121
21st to endDay
3312212335%75%
1980
October1st to 10thDay
4323223436%68%
1845
11th to 20thDay
221232345%6%71%
1800
21st to endDay
331332345%7%67%
1905
November1st to 10thDay
5%5%234245%6%7%57%
1674
11th to 20thDay
43134346%7%9%55%
1710
21st to endDay
25%34435%6%7%9%52%
1637
December1st to 10thDay
46%36%6%45%5%6%9%46%
1520
11th to 20thDay
5%9%38%7%47%6%8%10%31%
1928
21st to endDay
48%38%8%46%8%8%11%33%
2794
January1st to 10thNight
46%36%5%45%5%8%11%42%
2646
11th to 20thNight
25%37%6%46%6%7%8%47%
2562
21st to endNight
5%8%36%5%35%6%7%9%43%
2574
February1st to 10thNight
26%35%5%35%5%7%9%51%
2338
11th to 20thNight
25%35%436%5%7%11%50%
2098
21st to endNight
25%35%5%35%47%10%52%
1776
March1st to 10thNight
37%36%6%36%6%6%8%46%
2160
11th to 20thNight
16%36%5%35%5%6%11%49%
2031
21st to endNight
46%25%435%5%6%8%53%
2026
April1st to 10thNight
45%24435%5%9%9%51%
1800
11th to 20thNight
3324425%5%5%7%60%
1779
21st to endNight
5%5%2332335%7%62%
1800
May1st to 10thNight
5%5%1342345%6%61%
1659
11th to 20thNight
5%32342446%7%59%
1448
21st to endNight
45%25%5%4445%8%53%
1552
June1st to 10thNight
44145%25%35%6%60%
1440
11th to 20thNight
3213212245%75%
1440
21st to endNight
311222323476%
1440
July1st to 10thNight
1112213335%79%
1440
11th to 20thNight
111221333479%
1440
21st to endNight
331232333474%
1582
August1st to 10thNight
4213323346%69%
1629
11th to 20thNight
222212345%77%
1780
21st to endNight
21211113483%
1980
September1st to 10thNight
212111225%83%
1800
11th to 20thNight
3212212336%75%
1837
21st to endNight
2212222346%73%
1980
October1st to 10thNight
5%223323335%70%
2113
11th to 20thNight
2213323345%72%
2160
21st to endNight
4313212347%70%
2448
November1st to 10thNight
45%2442446%8%56%
2405
11th to 20thNight
331443446%9%58%
2470
21st to endNight
3435%3345%5%9%56%
2541
December1st to 10thNight
45%36%5%25%6%5%9%50%
2660
11th to 20thNight
6%7%47%6%47%6%9%11%33%
3276
21st to endNight
38%38%8%47%7%8%10%33%
4862

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
34%9%18%29%9%1
1519
11th to 20thDay
31%7%18%25%17%2
1459
21st to endDay
36%9%14%26%14%1
1781
February1st to 10thDay
30%6%15%29%16%4
1620
11th to 20thDay
29%5%15%30%18%3
1760
21st to endDay
25%8%18%28%18%4
1480
March1st to 10thDay
32%7%15%27%16%2
1800
11th to 20thDay
33%6%15%24%18%4
1926
21st to endDay
28%7%21%28%13%3
2330
April1st to 10thDay
29%6%13%27%19%6%
2160
11th to 20thDay
24%6%11%29%24%6%
2132
21st to endDay
23%412%32%25%4
2160
May1st to 10thDay
21%49%28%31%7%
2299
11th to 20thDay
25%38%25%30%9%
2444
21st to endDay
31%5%11%23%25%5%
2724
June1st to 10thDay
21%5%8%21%32%14%
2520
11th to 20thDay
14%3421%33%26%
2520
21st to endDay
13%2211%31%41%
2520
July1st to 10thDay
9%339%24%53%
2451
11th to 20thDay
9%229%25%53%
2445
21st to endDay
15%338%22%49%
2580
August1st to 10thDay
15%3211%24%45%
2291
11th to 20thDay
9%328%28%51%
2122
21st to endDay
8%117%31%51%
2376
September1st to 10thDay
7%218%28%53%
2160
11th to 20thDay
13%2417%34%30%
2121
21st to endDay
13%3318%36%26%
1980
October1st to 10thDay
19%37%20%34%18%
1845
11th to 20thDay
14%38%24%33%17%
1800
21st to endDay
17%48%30%30%12%
1905
November1st to 10thDay
24%6%11%26%25%7%
1674
11th to 20thDay
22%7%17%31%21%3
1710
21st to endDay
27%411%30%24%3
1637
December1st to 10thDay
32%7%16%27%16%3
1520
11th to 20thDay
44%9%12%23%10%1
1928
21st to endDay
38%9%18%25%9%1
2794
January1st to 10thNight
32%8%18%29%11%1
2646
11th to 20thNight
31%6%18%26%14%4
2562
21st to endNight
34%6%13%28%18%1
2574
February1st to 10thNight
28%5%14%31%18%4
2338
11th to 20thNight
26%6%13%32%21%2
2099
21st to endNight
26%6%16%32%15%4
1776
March1st to 10thNight
33%5%15%27%16%3
2160
11th to 20thNight
27%6%15%26%21%5%
2031
21st to endNight
26%7%20%28%15%3
2026
April1st to 10thNight
26%7%16%29%17%5%
1800
11th to 20thNight
23%5%14%30%19%8%
1779
21st to endNight
23%412%34%22%5%
1800
May1st to 10thNight
23%48%27%32%6%
1659
11th to 20thNight
22%5%11%29%23%9%
1448
21st to endNight
28%414%28%22%5%
1552
June1st to 10thNight
24%5%8%23%27%14%
1440
11th to 20thNight
12%37%20%34%24%
1440
21st to endNight
13%3314%29%38%
1440
July1st to 10thNight
9%239%27%50%
1400
11th to 20thNight
10%2210%24%52%
1392
21st to endNight
13%338%23%49%
1494
August1st to 10thNight
16%4412%24%40%
1620
11th to 20thNight
10%329%27%48%
1780
21st to endNight
9%128%31%49%
1980
September1st to 10thNight
8%127%30%51%
1800
11th to 20thNight
12%2418%34%29%
1837
21st to endNight
14%3318%33%29%
1980
October1st to 10thNight
18%28%20%30%21%
2113
11th to 20thNight
14%36%24%33%20%
2160
21st to endNight
15%38%29%31%14%
2448
November1st to 10thNight
24%6%11%28%22%9%
2405
11th to 20thNight
22%6%14%30%25%4
2470
21st to endNight
25%5%12%30%23%6%
2541
December1st to 10thNight
30%7%14%26%20%3
2660
11th to 20thNight
40%10%13%23%13%1
3276
21st to endNight
41%9%15%21%12%1
4862

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
11%7%27%33%17%5%
180
11th to 20thDay
6%9%17%38%22%8%
165
21st to endDay
6%417%39%25%9%
373
February1st to 10thDay
6%13%16%34%24%6%
340
11th to 20thDay
7%11%23%36%21%2
415
21st to endDay
5%12%26%36%19%2
346
March1st to 10thDay
9%11%25%37%13%5%
420
11th to 20thDay
7%14%25%29%19%6%
420
21st to endDay
9%17%26%31%15%3
462
April1st to 10thDay
10%15%25%26%18%5%
420
11th to 20thDay
9%21%24%25%16%6%
412
21st to endDay
10%19%22%24%18%7%
420
May1st to 10thDay
9%19%25%26%16%6%
423
11th to 20thDay
9%19%26%22%16%7%
448
21st to endDay
9%13%20%24%22%12%
485
June1st to 10thDay
6%14%25%20%25%10%
450
11th to 20thDay
7%14%29%24%19%7%
450
21st to endDay
49%24%26%27%9%
450
July1st to 10thDay
28%23%34%24%10%
446
11th to 20thDay
16%24%30%28%12%
444
21st to endDay
35%20%33%27%13%
487
August1st to 10thDay
48%21%28%26%13%
447
11th to 20thDay
28%20%32%23%15%
437
21st to endDay
25%24%33%27%9%
495
September1st to 10thDay
27%21%31%29%10%
450
11th to 20thDay
6%8%21%32%24%9%
450
21st to endDay
48%22%32%28%6%
450
October1st to 10thDay
6%10%22%28%24%9%
450
11th to 20thDay
5%10%18%28%30%9%
450
21st to endDay
6%10%18%31%26%9%
420
November1st to 10thDay
11%6%18%28%25%12%
270
11th to 20thDay
36%19%32%30%11%
270
21st to endDay
5%7%21%28%30%9%
235
December1st to 10thDay
7%8%18%31%24%11%
180
11th to 20thDay
6%5%21%37%22%9%
180
21st to endDay
11%9%16%37%22%5%
198
January1st to 10thNight
9%320%40%23%6%
760
11th to 20thNight
4418%47%22%4
732
21st to endNight
7%414%46%23%6%
792
February1st to 10thNight
45%18%46%24%3
720
11th to 20thNight
5%418%47%22%3
704
21st to endNight
5%7%21%47%18%2
592
March1st to 10thNight
7%5%21%44%19%3
720
11th to 20thNight
47%21%38%27%3
720
21st to endNight
6%7%28%39%18%3
792
April1st to 10thNight
5%9%22%40%23%2
720
11th to 20thNight
411%22%38%21%4
711
21st to endNight
6%9%21%37%24%3
720
May1st to 10thNight
7%11%20%40%20%3
579
11th to 20thNight
35%24%41%25%4
386
21st to endNight
5%416%45%27%4
389
June1st to 10thNight
6%417%41%28%4
360
11th to 20thNight
4419%45%26%2
360
21st to endNight
3113%53%29%2
360
July1st to 10thNight
110%53%33%3
350
11th to 20thNight
113%54%32%
348
21st to endNight
425%48%40%2
400
August1st to 10thNight
416%43%42%4
555
11th to 20thNight
2213%43%37%4
712
21st to endNight
2113%46%34%3
792
September1st to 10thNight
2211%42%39%5%
720
11th to 20thNight
3313%36%37%8%
720
21st to endNight
3413%39%31%11%
720
October1st to 10thNight
5%412%42%31%6%
720
11th to 20thNight
46%11%41%33%6%
720
21st to endNight
5%414%36%32%10%
792
November1st to 10thNight
7%416%37%29%7%
740
11th to 20thNight
5%415%47%24%4
760
21st to endNight
46%17%44%25%5%
760
December1st to 10thNight
8%418%46%20%4
760
11th to 20thNight
7%6%19%42%23%3
760
21st to endNight
8%7%23%45%16%1
836
Page generated at 2024-01-10 16:35:25. Version ac07

Copyright 2024 Attilla Danko


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