Avonmore
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Avonmore clear sky chart from 2005-11-05 to 2017-09-10.

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
30%
14638
13%
46781
8%
14607
36%
14607
16%
33868

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 15thNight
16%
720
6%
2506
3%
716
19%
716
7%
2055
January16th to endNight
21%
768
9%
2664
6%
768
26%
768
10%
2056
February1st to 15thNight
17%
704
9%
2287
5%
701
24%
701
9%
1807
February16th to endNight
23%
631
13%
1922
7%
631
32%
631
13%
1481
March1st to 15thNight
20%
720
13%
2130
7%
720
27%
720
14%
1621
March16th to endNight
30%
768
20%
2013
9%
768
37%
768
22%
1439
April1st to 15thNight
26%
718
16%
1796
6%
718
31%
718
20%
1343
April16th to endNight
29%
659
17%
1739
6%
659
36%
659
22%
1239
May1st to 15thNight
33%
360
16%
1440
13%
360
42%
360
15%
966
May16th to endNight
35%
374
12%
1497
9%
374
45%
374
18%
937
June1st to 15thNight
36%
360
9%
1440
9%
360
44%
360
13%
994
June16th to endNight
44%
360
9%
1440
12%
360
49%
360
20%
905
July1st to 15thNight
54%
340
14%
1360
21%
340
60%
340
27%
760
July16th to endNight
53%
376
13%
1418
15%
354
58%
354
24%
836
August1st to 15thNight
52%
413
14%
1484
13%
411
56%
411
22%
947
August16th to endNight
51%
738
20%
1884
11%
738
55%
738
35%
1211
September1st to 15thNight
47%
700
15%
1750
7%
700
48%
700
27%
1230
September16th to endNight
45%
657
21%
1784
14%
657
49%
657
30%
1168
October1st to 15thNight
34%
660
18%
1980
12%
660
43%
660
20%
1384
October16th to endNight
25%
704
11%
2221
6%
704
32%
704
13%
1681
November1st to 15thNight
28%
700
16%
2298
11%
700
36%
700
16%
1636
November16th to endNight
21%
720
11%
2520
8%
720
27%
720
10%
1912
December1st to 15thNight
17%
720
7%
2520
2%
720
22%
720
8%
2053
December16th to endNight
12%
768
8%
2688
3%
768
18%
768
7%
2207

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
18%9%36%5%3445%6%32%
47861
Night
18%10%46%5%34446%31%
46950
Cloud CoverDay
19%9%36%5%34446%32%
47870
Night
19%10%47%5%34445%31%
46956
TransparencyDay
52%5%11%19%9%1
47548
Night
54%5%11%18%9%1
46781
SeeingDay
23%10%27%23%11%3
5503
Night
23%9%28%26%9%
14639

By Month

Percentage Cloud Cover NE (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 15thDay
23%16%6%8%5%2444419%
1432
16th to endDay
14%17%5%7%6%45%5%46%22%
1557
February1st to 15thDay
16%14%5%11%6%35%5%46%21%
1575
16th to endDay
19%13%5%7%6%3434425%
1551
March1st to 15thDay
18%12%49%7%35%33327%
1819
16th to endDay
19%7%345%14445%39%
2211
April1st to 15thDay
24%11%35%5%2224433%
2152
16th to endDay
21%8%35%423345%35%
2229
May1st to 15thDay
20%8%26%42445%6%33%
2511
16th to endDay
17%7%35%5%35%45%6%35%
2618
June1st to 15thDay
23%6%35%5%3445%7%29%
2520
16th to endDay
19%6%245%35%5%7%8%31%
2520
July1st to 15thDay
14%435%425%5%6%8%39%
2520
16th to endDay
14%425%5%36%6%7%8%35%
2654
August1st to 15thDay
12%7%25%6%35%5%6%8%35%
2466
16th to endDay
10%5%245%35%5%5%8%43%
2306
September1st to 15thDay
17%5%25%42336%6%40%
2098
16th to endDay
17%5%14323337%44%
1846
October1st to 15thDay
21%7%26%5%24436%34%
1650
16th to endDay
26%12%37%5%3433424%
1650
November1st to 15thDay
15%9%46%5%3445%7%32%
1560
16th to endDay
23%12%38%5%33336%26%
1440
December1st to 15thDay
25%14%5%7%7%44435%17%
1440
16th to endDay
24%14%6%8%6%4433320%
1536
January1st to 15thNight
20%16%5%10%7%35%345%17%
2506
16th to endNight
15%16%6%8%6%34345%24%
2664
February1st to 15thNight
14%14%5%12%7%45%45%5%21%
2285
16th to endNight
17%14%5%7%6%3434427%
1922
March1st to 15thNight
20%12%5%7%5%25%32429%
2117
16th to endNight
17%10%35%5%2333439%
2013
April1st to 15thNight
25%7%345%23345%33%
1796
16th to endNight
19%7%35%434336%37%
1739
May1st to 15thNight
21%7%35%425%35%5%34%
1440
16th to endNight
17%7%3433445%7%37%
1495
June1st to 15thNight
22%6%25%6%35%45%8%29%
1440
16th to endNight
17%5%245%2447%8%36%
1440
July1st to 15thNight
10%4134345%7%10%43%
1440
16th to endNight
10%4235%25%6%7%8%42%
1514
August1st to 15thNight
10%8%25%5%35%46%9%38%
1494
16th to endNight
11%5%2442445%8%46%
1884
September1st to 15thNight
16%6%25%44445%6%39%
1750
16th to endNight
17%424323345%47%
1784
October1st to 15thNight
20%8%24424446%36%
1980
16th to endNight
26%9%46%5%34346%26%
2221
November1st to 15thNight
21%10%25%5%2434433%
2298
16th to endNight
21%12%5%8%5%34345%25%
2520
December1st to 15thNight
23%15%5%7%6%245%45%19%
2520
16th to endNight
25%16%5%7%5%3443419%
2688

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 15thDay
22%16%7%8%6%3335%418%
1432
16th to endDay
14%17%6%7%6%45%5%45%21%
1557
February1st to 15thDay
16%15%5%10%8%445%5%420%
1575
16th to endDay
20%14%6%7%7%2433425%
1551
March1st to 15thDay
19%12%5%9%7%3433327%
1829
16th to endDay
20%7%35%423335%38%
2210
April1st to 15thDay
24%10%46%5%22225%33%
2152
16th to endDay
21%8%26%424346%35%
2229
May1st to 15thDay
20%7%34434447%34%
2511
16th to endDay
18%6%35%5%35%5%46%35%
2618
June1st to 15thDay
23%6%35%5%3445%6%30%
2520
16th to endDay
19%5%245%25%6%6%9%31%
2520
July1st to 15thDay
13%5%345%35%5%6%7%39%
2520
16th to endDay
13%5%245%36%6%7%8%36%
2654
August1st to 15thDay
12%6%25%6%46%5%6%7%35%
2466
16th to endDay
10%5%245%35%5%5%7%43%
2306
September1st to 15thDay
18%5%245%3345%7%39%
2098
16th to endDay
16%6%235%33336%44%
1846
October1st to 15thDay
21%7%25%5%33446%34%
1650
16th to endDay
28%10%48%5%3333424%
1650
November1st to 15thDay
15%9%46%6%35%5%47%31%
1560
16th to endDay
23%13%47%5%23335%26%
1440
December1st to 15thDay
24%15%5%8%7%34435%16%
1440
16th to endDay
25%16%5%7%6%3423320%
1536
January1st to 15thNight
19%18%5%11%6%35%34417%
2506
16th to endNight
14%17%6%9%6%45%34424%
2664
February1st to 15thNight
14%14%6%13%7%3444420%
2278
16th to endNight
18%13%48%7%345%3427%
1922
March1st to 15thNight
21%13%47%5%3432429%
2130
16th to endNight
18%9%46%42324339%
2013
April1st to 15thNight
24%8%35%423435%32%
1796
16th to endNight
20%6%35%434445%37%
1739
May1st to 15thNight
22%7%345%24447%33%
1440
16th to endNight
18%6%25%325%45%7%37%
1495
June1st to 15thNight
22%6%25%6%35%5%6%7%29%
1440
16th to endNight
16%5%35%4245%7%9%35%
1440
July1st to 15thNight
10%3244345%7%9%43%
1440
16th to endNight
10%5%14435%7%7%7%42%
1514
August1st to 15thNight
11%7%26%5%3446%9%38%
1494
16th to endNight
12%4245%2345%7%47%
1884
September1st to 15thNight
16%5%35%434446%40%
1750
16th to endNight
17%5%24324335%46%
1784
October1st to 15thNight
20%8%35%424446%35%
1980
16th to endNight
27%9%37%5%34336%26%
2221
November1st to 15thNight
20%9%36%5%34345%32%
2298
16th to endNight
21%12%48%5%34345%24%
2520
December1st to 15thNight
23%15%5%7%7%24345%19%
2520
16th to endNight
26%16%5%8%5%3333418%
2688

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 15thDay
68%49%10%5%
1433
16th to endDay
63%412%12%6%
1557
February1st to 15thDay
65%49%17%2
1577
16th to endDay
62%310%12%9%
1551
March1st to 15thDay
62%311%13%7%1
1829
16th to endDay
48%48%17%15%5%
2211
April1st to 15thDay
55%26%19%12%2
2152
16th to endDay
50%47%18%14%4
2229
May1st to 15thDay
49%5%9%19%13%2
2511
16th to endDay
48%6%11%20%12%1
2622
June1st to 15thDay
53%6%11%20%9%
2520
16th to endDay
47%7%12%20%10%
2520
July1st to 15thDay
39%7%13%28%11%
2371
16th to endDay
42%8%16%23%9%
2487
August1st to 15thDay
45%8%16%21%8%
2452
16th to endDay
37%6%16%28%11%
2306
September1st to 15thDay
42%6%12%25%12%
2098
16th to endDay
41%5%11%31%10%
1846
October1st to 15thDay
50%5%12%21%9%
1650
16th to endDay
64%410%13%6%
1650
November1st to 15thDay
51%6%13%18%9%
1560
16th to endDay
61%5%10%15%6%
1440
December1st to 15thDay
70%5%11%10%1
1440
16th to endDay
69%5%9%10%4
1536
January1st to 15thNight
70%410%9%4
2506
16th to endNight
63%411%13%6%
2664
February1st to 15thNight
65%410%15%4
2287
16th to endNight
60%5%8%16%9%
1922
March1st to 15thNight
60%39%17%8%1
2130
16th to endNight
49%48%18%14%4
2013
April1st to 15thNight
53%47%19%14%
1796
16th to endNight
47%5%7%18%16%3
1739
May1st to 15thNight
50%6%7%15%16%4
1440
16th to endNight
44%6%13%20%13%2
1497
June1st to 15thNight
52%6%12%17%10%
1440
16th to endNight
42%7%14%20%13%
1440
July1st to 15thNight
32%7%14%29%15%
1360
16th to endNight
35%8%15%24%14%
1418
August1st to 15thNight
41%7%17%21%11%
1484
16th to endNight
35%5%14%31%12%
1884
September1st to 15thNight
44%6%11%25%12%
1750
16th to endNight
39%5%10%32%12%
1784
October1st to 15thNight
48%6%10%23%10%
1980
16th to endNight
60%412%16%5%
2221
November1st to 15thNight
53%5%13%16%9%1
2298
16th to endNight
61%5%11%15%5%
2520
December1st to 15thNight
67%6%10%12%2
2520
16th to endNight
68%6%9%10%4
2688

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 15thDay
26%18%20%25%10%
60
16th to endDay
37%5%32%17%5%
67
February1st to 15thDay
36%22%28%11%1
90
16th to endDay
30%13%30%21%2
210
March1st to 15thDay
25%13%33%22%5%
270
16th to endDay
23%11%30%22%8%2
288
April1st to 15thDay
32%14%27%18%7%1
270
16th to endDay
22%15%23%22%10%4
270
May1st to 15thDay
27%9%29%17%12%3
288
16th to endDay
19%15%32%17%12%1
331
June1st to 15thDay
27%7%28%24%7%3
315
16th to endDay
23%7%28%26%12%2
315
July1st to 15thDay
15%6%25%32%17%4
305
16th to endDay
15%423%34%18%3
326
August1st to 15thDay
16%421%34%16%5%
313
16th to endDay
13%5%22%31%15%12%
332
September1st to 15thDay
19%6%22%22%17%12%
294
16th to endDay
18%8%27%20%16%8%
254
October1st to 15thDay
23%10%25%23%13%3
255
16th to endDay
36%9%24%21%7%
252
November1st to 15thDay
19%12%33%20%13%1
214
16th to endDay
35%11%25%20%8%
60
December1st to 15thDay
28%15%31%20%5%
60
16th to endDay
40%21%29%6%1
64
January1st to 15thNight
27%15%32%19%5%
720
16th to endNight
22%13%32%25%6%
768
February1st to 15thNight
22%15%34%24%3
704
16th to endNight
25%10%33%24%5%
631
March1st to 15thNight
27%13%33%21%4
720
16th to endNight
21%10%30%28%8%
768
April1st to 15thNight
27%10%30%26%5%
718
16th to endNight
24%10%31%24%8%
659
May1st to 15thNight
27%429%27%8%1
360
16th to endNight
18%7%34%28%10%
375
June1st to 15thNight
24%6%23%37%8%
360
16th to endNight
16%229%34%14%1
360
July1st to 15thNight
11%324%40%19%
340
16th to endNight
11%226%42%15%1
376
August1st to 15thNight
14%418%41%19%2
413
16th to endNight
13%322%36%21%1
738
September1st to 15thNight
20%421%35%16%1
700
16th to endNight
20%6%24%24%21%1
657
October1st to 15thNight
23%6%29%26%12%
660
16th to endNight
32%11%25%23%7%
704
November1st to 15thNight
25%10%29%23%10%
700
16th to endNight
27%15%27%20%9%
720
December1st to 15thNight
30%14%29%20%4
720
16th to endNight
33%13%32%16%3
768
Page generated at 2017-09-11 19:35:28. Version ac04

Copyright 2017 A. Danko


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