Ashland
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ashland 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
52%
22977
19%
74682
17%
22926
54%
22926
24%
47994

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%
757
9%
2644
7%
756
33%
756
11%
2045
January11th to 20thNight
42%
720
16%
2432
14%
720
46%
720
18%
1688
January21st to endNight
44%
792
20%
2574
20%
792
48%
792
19%
1789
February1st to 10thNight
41%
720
14%
2340
14%
720
44%
720
18%
1644
February11th to 20thNight
39%
702
13%
2274
13%
700
43%
700
16%
1653
February21st to endNight
37%
592
13%
1804
10%
592
41%
592
15%
1358
March1st to 10thNight
35%
720
9%
2039
7%
720
37%
720
15%
1566
March11th to 20thNight
39%
720
14%
1980
10%
720
42%
720
18%
1489
March21st to endNight
34%
792
7%
2147
5%
792
35%
792
14%
1709
April1st to 10thNight
37%
720
12%
1800
6%
720
38%
720
18%
1392
April11th to 20thNight
40%
711
14%
1779
8%
711
42%
711
21%
1329
April21st to endNight
44%
634
12%
1714
7%
634
46%
634
23%
1204
May1st to 10thNight
50%
504
15%
1584
12%
504
52%
504
25%
1010
May11th to 20thNight
53%
354
17%
1416
20%
354
56%
354
20%
879
May21st to endNight
49%
389
11%
1552
11%
388
53%
388
17%
1014
June1st to 10thNight
59%
360
11%
1440
17%
360
61%
360
21%
880
June11th to 20thNight
57%
360
18%
1440
23%
360
62%
360
28%
764
June21st to endNight
78%
360
26%
1440
39%
360
80%
360
46%
600
July1st to 10thNight
82%
350
27%
1400
39%
350
86%
350
53%
531
July11th to 20thNight
81%
348
35%
1392
46%
348
85%
348
57%
504
July21st to endNight
89%
519
37%
1607
40%
491
91%
491
71%
614
August1st to 10thNight
87%
537
34%
1602
30%
534
88%
534
64%
698
August11th to 20thNight
87%
534
39%
1602
31%
534
89%
534
68%
671
August21st to endNight
75%
778
39%
1966
25%
778
77%
778
70%
938
September1st to 10thNight
78%
720
40%
1800
26%
720
79%
720
74%
850
September11th to 20thNight
73%
720
34%
1800
25%
720
75%
720
56%
974
September21st to endNight
67%
720
29%
2063
26%
720
70%
720
44%
1128
October1st to 10thNight
63%
720
21%
2160
20%
720
67%
720
39%
1216
October11th to 20thNight
63%
720
26%
2160
28%
720
65%
720
35%
1260
October21st to endNight
56%
792
23%
2376
22%
792
59%
792
28%
1503
November1st to 10thNight
42%
740
17%
2367
17%
740
44%
740
18%
1671
November11th to 20thNight
42%
760
12%
2646
12%
760
45%
760
15%
1919
November21st to endNight
43%
760
14%
2660
12%
760
47%
760
19%
1788
December1st to 10thNight
44%
760
17%
2660
17%
760
48%
760
19%
1784
December11th to 20thNight
35%
760
11%
3212
9%
759
39%
759
10%
2476
December21st to endNight
25%
832
8%
4810
9%
817
30%
817
6%
3456

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
9%9%35%5%3445%6%47%
74699
Night
10%11%36%5%3445%6%43%
74987
TransparencyDay
36%7%11%20%18%8%
74410
Night
40%8%11%19%15%6%
74798
SeeingDay
16%15%28%26%12%3
13798
Night
15%9%19%32%22%3
22986

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
13%14%48%6%46%6%6%8%25%
1511
11th to 20thDay
13%11%46%6%47%6%6%6%33%
1526
21st to endDay
12%14%46%43346%8%36%
1782
February1st to 10thDay
7%13%48%6%46%6%8%6%31%
1620
11th to 20thDay
9%15%5%6%6%35%45%7%35%
1575
21st to endDay
11%19%6%8%7%34346%28%
1451
March1st to 10thDay
11%17%6%9%9%45%5%6%6%24%
1919
11th to 20thDay
12%16%5%7%6%35%46%7%28%
1980
21st to endDay
14%17%5%8%8%36%5%6%6%23%
2208
April1st to 10thDay
13%18%6%8%7%34436%26%
2160
11th to 20thDay
15%16%5%7%5%34447%30%
2129
21st to endDay
10%14%47%5%3446%7%37%
2243
May1st to 10thDay
11%10%35%434347%45%
2373
11th to 20thDay
13%9%46%4345%5%8%40%
2477
21st to endDay
16%11%35%43445%8%37%
2723
June1st to 10thDay
12%8%35%5%3445%8%43%
2520
11th to 20thDay
8%6%245%3345%7%54%
2520
21st to endDay
5%312223245%69%
2520
July1st to 10thDay
3212212235%77%
2520
11th to 20thDay
321221332478%
2520
21st to endDay
111221223381%
2613
August1st to 10thDay
2212223445%74%
2328
11th to 20thDay
1212212236%78%
2298
21st to endDay
2212112335%78%
2390
September1st to 10thDay
3212212245%78%
2160
11th to 20thDay
441342446%7%61%
2160
21st to endDay
7%41432335%7%61%
1890
October1st to 10thDay
9%6%25%5%24445%55%
1800
11th to 20thDay
9%7%244335%5%6%51%
1800
21st to endDay
10%9%26%5%34447%46%
1980
November1st to 10thDay
15%12%46%6%345%48%33%
1711
11th to 20thDay
16%9%37%5%46%7%8%8%28%
1530
21st to endDay
12%14%36%5%45%45%7%35%
1520
December1st to 10thDay
11%10%36%6%345%6%7%39%
1520
11th to 20thDay
14%15%47%6%45%6%6%9%23%
1928
21st to endDay
13%16%48%7%46%7%6%8%21%
2794
January1st to 10thNight
14%12%5%9%7%47%6%7%7%23%
2644
11th to 20thNight
11%12%5%6%5%35%5%6%7%35%
2432
21st to endNight
12%12%5%6%5%35%5%6%7%34%
2574
February1st to 10thNight
10%13%5%8%6%35%5%6%6%33%
2340
11th to 20thNight
11%16%6%6%6%35%446%33%
2272
21st to endNight
10%17%7%9%6%35%5%5%6%28%
1804
March1st to 10thNight
13%16%5%9%6%45%5%5%7%26%
2039
11th to 20thNight
11%14%5%8%7%46%5%5%8%29%
1980
21st to endNight
12%18%7%8%6%5%5%35%6%25%
2147
April1st to 10thNight
12%16%6%9%5%345%5%6%28%
1800
11th to 20thNight
12%16%5%6%5%235%5%6%34%
1779
21st to endNight
15%15%45%41345%10%34%
1714
May1st to 10thNight
11%11%27%5%23446%43%
1584
11th to 20thNight
11%10%26%6%35%5%5%7%40%
1416
21st to endNight
14%12%46%5%245%5%8%36%
1552
June1st to 10thNight
12%8%25%5%35%45%7%43%
1440
11th to 20thNight
7%8%35%5%33346%53%
1440
21st to endNight
5%413322245%70%
1440
July1st to 10thNight
2312223335%74%
1440
11th to 20thNight
321222222477%
1440
21st to endNight
121122222383%
1701
August1st to 10thNight
2212223345%75%
1611
11th to 20thNight
12221232480%
1602
21st to endNight
2212112235%78%
1966
September1st to 10thNight
3311112235%79%
1800
11th to 20thNight
5%31332346%6%64%
1800
21st to endNight
8%6%23323345%61%
2063
October1st to 10thNight
7%7%34424346%57%
2160
11th to 20thNight
9%7%25%424446%54%
2160
21st to endNight
10%7%35%5%3346%6%46%
2376
November1st to 10thNight
15%13%37%5%345%46%33%
2367
11th to 20thNight
17%11%26%6%46%6%7%8%28%
2646
21st to endNight
13%13%45%5%3445%7%37%
2660
December1st to 10thNight
12%10%36%5%345%6%7%37%
2660
11th to 20thNight
11%15%5%8%7%47%6%6%7%23%
3276
21st to endNight
14%16%5%8%6%45%5%5%7%24%
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
56%10%15%11%6%1
1511
11th to 20thDay
50%7%10%15%10%8%
1526
21st to endDay
47%7%10%19%12%5%
1782
February1st to 10thDay
49%11%16%14%9%2
1620
11th to 20thDay
49%8%12%19%9%2
1584
21st to endDay
58%6%9%16%9%2
1451
March1st to 10thDay
58%10%11%14%7%
1919
11th to 20thDay
53%8%11%16%9%2
1980
21st to endDay
60%9%13%13%6%1
2208
April1st to 10thDay
58%8%12%13%8%2
2160
11th to 20thDay
51%8%13%14%9%4
2132
21st to endDay
44%8%15%21%11%1
2243
May1st to 10thDay
37%7%13%28%13%1
2373
11th to 20thDay
41%7%14%25%12%2
2480
21st to endDay
42%9%17%23%9%1
2724
June1st to 10thDay
38%8%15%28%11%1
2520
11th to 20thDay
26%8%11%35%16%3
2520
21st to endDay
18%49%30%29%10%
2520
July1st to 10thDay
11%38%28%30%21%
2451
11th to 20thDay
12%36%21%34%25%
2445
21st to endDay
9%3417%43%24%
2468
August1st to 10thDay
11%49%27%32%15%
2312
11th to 20thDay
10%37%22%41%18%
2298
21st to endDay
11%37%24%37%18%
2390
September1st to 10thDay
11%3421%33%28%
2160
11th to 20thDay
22%5%9%24%28%13%
2160
21st to endDay
23%6%10%22%24%16%
1890
October1st to 10thDay
30%6%12%17%22%14%
1800
11th to 20thDay
32%7%12%20%22%8%
1800
21st to endDay
39%7%11%18%18%9%
1980
November1st to 10thDay
49%7%12%17%13%2
1711
11th to 20thDay
51%10%13%12%10%4
1530
21st to endDay
50%5%12%14%12%6%
1520
December1st to 10thDay
44%8%13%18%14%3
1520
11th to 20thDay
57%9%15%12%7%1
1928
21st to endDay
59%11%11%14%41
2794
January1st to 10thNight
58%10%12%11%7%2
2644
11th to 20thNight
49%7%10%15%11%8%
2432
21st to endNight
48%8%9%15%16%5%
2574
February1st to 10thNight
49%7%13%17%11%2
2340
11th to 20thNight
52%8%10%17%10%2
2274
21st to endNight
53%10%12%13%8%2
1804
March1st to 10thNight
56%8%12%15%8%1
2039
11th to 20thNight
52%9%11%16%12%1
1980
21st to endNight
57%11%14%13%5%
2147
April1st to 10thNight
53%9%15%15%7%1
1800
11th to 20thNight
48%10%15%15%8%4
1779
21st to endNight
45%9%18%20%7%2
1714
May1st to 10thNight
38%9%16%25%10%2
1584
11th to 20thNight
38%11%15%27%6%2
1416
21st to endNight
43%11%20%22%5%
1552
June1st to 10thNight
38%10%16%31%5%
1440
11th to 20thNight
28%9%15%33%13%1
1440
21st to endNight
17%5%12%39%21%5%
1440
July1st to 10thNight
12%6%9%32%25%17%
1400
11th to 20thNight
13%35%24%37%19%
1392
21st to endNight
9%2422%49%15%
1607
August1st to 10thNight
11%48%35%31%11%
1602
11th to 20thNight
10%37%31%37%13%
1602
21st to endNight
10%48%30%35%14%
1966
September1st to 10thNight
9%37%24%34%24%
1800
11th to 20thNight
19%5%12%25%29%11%
1800
21st to endNight
26%410%23%18%19%
2063
October1st to 10thNight
27%7%12%18%25%12%
2160
11th to 20thNight
32%6%11%20%21%11%
2160
21st to endNight
35%10%13%15%15%12%
2376
November1st to 10thNight
50%7%11%14%12%5%
2367
11th to 20thNight
51%10%11%13%10%4
2646
21st to endNight
47%7%11%13%15%7%
2660
December1st to 10thNight
44%9%9%20%15%2
2660
11th to 20thNight
59%9%8%13%10%1
3276
21st to endNight
56%10%11%15%6%2
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
31%18%28%17%42
178
11th to 20thDay
24%19%28%16%11%3
246
21st to endDay
21%18%24%23%13%1
374
February1st to 10thDay
19%19%30%24%8%1
340
11th to 20thDay
24%22%24%23%7%
335
21st to endDay
23%23%29%20%4
334
March1st to 10thDay
26%22%28%19%5%
420
11th to 20thDay
23%19%27%22%10%
420
21st to endDay
25%23%28%18%5%
462
April1st to 10thDay
25%22%28%18%7%1
420
11th to 20thDay
29%20%26%17%6%2
412
21st to endDay
22%21%27%20%9%2
420
May1st to 10thDay
18%21%30%21%8%2
423
11th to 20thDay
25%19%23%20%10%3
448
21st to endDay
20%13%28%24%10%5%
485
June1st to 10thDay
16%19%28%20%13%4
450
11th to 20thDay
14%19%30%24%11%2
450
21st to endDay
412%33%30%15%6%
450
July1st to 10thDay
6%12%37%26%14%5%
446
11th to 20thDay
38%39%30%14%6%
444
21st to endDay
17%34%32%17%9%
487
August1st to 10thDay
28%33%32%17%8%
447
11th to 20thDay
211%25%35%19%8%
437
21st to endDay
49%28%36%18%5%
495
September1st to 10thDay
410%27%37%19%3
450
11th to 20thDay
7%12%26%36%17%2
450
21st to endDay
10%12%29%32%17%1
450
October1st to 10thDay
13%13%26%28%18%1
450
11th to 20thDay
16%11%21%28%23%1
450
21st to endDay
17%16%25%24%16%2
495
November1st to 10thDay
19%15%20%31%14%1
307
11th to 20thDay
17%13%23%33%11%3
185
21st to endDay
19%14%26%29%13%
180
December1st to 10thDay
24%11%30%22%9%4
180
11th to 20thDay
27%13%24%26%8%2
180
21st to endDay
24%18%26%23%10%
198
January1st to 10thNight
22%13%29%25%9%2
760
11th to 20thNight
17%13%24%29%14%2
720
21st to endNight
19%10%20%34%14%3
792
February1st to 10thNight
17%12%23%36%12%1
720
11th to 20thNight
20%10%23%31%14%1
704
21st to endNight
17%14%25%33%11%1
592
March1st to 10thNight
23%14%23%28%10%3
720
11th to 20thNight
18%12%23%29%16%2
720
21st to endNight
22%16%21%28%13%2
792
April1st to 10thNight
20%14%22%29%13%1
720
11th to 20thNight
20%12%22%26%16%3
711
21st to endNight
24%8%17%30%19%3
634
May1st to 10thNight
17%9%16%34%22%1
504
11th to 20thNight
15%6%16%37%23%2
354
21st to endNight
21%6%17%29%25%2
389
June1st to 10thNight
14%7%14%37%28%1
360
11th to 20thNight
10%6%21%40%22%1
360
21st to endNight
7%210%43%37%1
360
July1st to 10thNight
2211%38%46%1
350
11th to 20thNight
4110%46%38%1
348
21st to endNight
115%34%52%6%
519
August1st to 10thNight
315%34%50%7%
537
11th to 20thNight
316%36%46%8%
534
21st to endNight
3317%37%37%4
778
September1st to 10thNight
3314%37%37%6%
720
11th to 20thNight
6%313%35%36%6%
720
21st to endNight
12%413%34%30%7%
720
October1st to 10thNight
10%317%37%29%4
720
11th to 20thNight
12%5%14%37%26%5%
720
21st to endNight
14%7%18%33%22%6%
792
November1st to 10thNight
21%8%22%31%14%4
740
11th to 20thNight
21%9%22%34%12%1
760
21st to endNight
19%9%24%31%16%2
760
December1st to 10thNight
18%13%20%33%13%2
760
11th to 20thNight
22%15%23%27%11%2
760
21st to endNight
26%20%24%23%7%1
836
Page generated at 2024-01-07 07:06:51. Version ac07

Copyright 2024 Attilla Danko


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