Dornoch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dornoch clear sky chart from 2005-11-05 to

2017-09-12
.

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%
15070
11%
46663
7%
15034
34%
15034
14%
35237

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
9%
880
3%
2601
1%
880
11%
880
4%
2342
January16th to endNight
15%
768
4%
2496
2%
768
16%
768
5%
2208
February1st to 15thNight
15%
701
4%
2287
1%
701
18%
701
5%
1983
February16th to endNight
18%
631
8%
1982
3%
631
22%
631
9%
1600
March1st to 15thNight
20%
720
11%
2011
6%
720
24%
720
13%
1593
March16th to endNight
33%
768
18%
2112
10%
768
39%
768
21%
1510
April1st to 15thNight
25%
679
14%
1814
5%
679
30%
679
19%
1340
April16th to endNight
35%
540
17%
1620
10%
540
39%
540
20%
1119
May1st to 15thNight
41%
534
15%
1614
10%
534
46%
534
22%
1093
May16th to endNight
45%
374
16%
1497
14%
374
56%
374
23%
891
June1st to 15thNight
42%
360
11%
1329
11%
360
49%
360
20%
832
June16th to endNight
49%
360
14%
1260
15%
360
55%
360
26%
761
July1st to 15thNight
61%
340
18%
1190
22%
340
64%
340
34%
640
July16th to endNight
54%
535
14%
1545
12%
502
56%
502
29%
942
August1st to 15thNight
59%
539
16%
1609
11%
536
62%
536
29%
1004
August16th to endNight
55%
582
20%
1728
15%
582
58%
582
30%
1085
September1st to 15thNight
49%
707
16%
1829
9%
707
52%
707
30%
1225
September16th to endNight
50%
657
17%
1815
12%
657
52%
657
27%
1206
October1st to 15thNight
34%
660
14%
1971
10%
660
38%
660
17%
1429
October16th to endNight
21%
704
8%
2139
4%
704
26%
704
10%
1743
November1st to 15thNight
24%
700
13%
2363
11%
700
29%
700
13%
1785
November16th to endNight
20%
720
7%
2520
6%
720
23%
720
8%
2065
December1st to 15thNight
10%
720
2%
2520
1%
720
11%
720
3%
2282
December16th to endNight
7%
891
3%
2811
0%
891
9%
891
3%
2559

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
17%11%47%6%34446%28%
48000
Night
17%11%5%8%6%34445%27%
46834
Cloud CoverDay
17%11%47%6%34446%28%
48010
Night
16%12%5%8%6%34445%27%
46838
TransparencyDay
55%5%11%16%9%
47689
Night
58%5%10%15%8%
46663
SeeingDay
21%9%27%23%13%5%
5719
Night
22%10%29%26%10%1
15079

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
17%18%9%15%9%4432310%
1333
16th to endDay
12%19%9%15%10%5%443410%
1728
February1st to 15thDay
14%18%8%15%9%4444310%
1575
16th to endDay
15%20%7%12%8%45%44313%
1488
March1st to 15thDay
15%12%6%10%9%35%345%24%
1937
16th to endDay
15%9%47%6%35%45%6%30%
2112
April1st to 15thDay
21%12%5%5%3235%45%29%
2146
16th to endDay
19%10%34323347%36%
2340
May1st to 15thDay
19%8%24424446%37%
2337
16th to endDay
15%6%245%3445%7%40%
2618
June1st to 15thDay
16%6%25%43445%8%36%
2628
16th to endDay
16%5%25%5%35%5%5%8%36%
2700
July1st to 15thDay
13%435%4345%6%8%40%
2700
16th to endDay
12%5%25%6%35%5%7%9%36%
2515
August1st to 15thDay
12%6%26%7%36%46%8%36%
2340
16th to endDay
13%5%25%6%35%6%5%8%36%
2462
September1st to 15thDay
17%8%35%5%23446%36%
2050
16th to endDay
18%6%24433448%37%
1815
October1st to 15thDay
24%9%35%434345%29%
1658
16th to endDay
32%14%46%5%2443416%
1733
November1st to 15thDay
17%17%5%6%6%34335%24%
1495
16th to endDay
21%21%6%9%5%3445%413%
1440
December1st to 15thDay
18%23%11%14%7%35%2346%
1440
16th to endDay
18%25%10%12%8%242237%
1410
January1st to 15thNight
20%17%8%14%10%343339%
2601
16th to endNight
14%16%9%13%11%5%6%43410%
2496
February1st to 15thNight
13%17%10%14%10%35%43313%
2285
16th to endNight
15%13%8%13%8%34436%19%
1982
March1st to 15thNight
16%12%6%10%7%25%435%25%
1999
16th to endNight
15%9%5%7%5%3333437%
2112
April1st to 15thNight
20%11%45%413346%32%
1814
16th to endNight
17%9%35%5%25%436%36%
1620
May1st to 15thNight
17%6%26%5%23447%37%
1614
16th to endNight
12%5%14425%5%6%7%42%
1495
June1st to 15thNight
15%6%345%2346%8%38%
1329
16th to endNight
13%42442446%9%43%
1260
July1st to 15thNight
9%42432445%8%50%
1260
16th to endNight
9%424425%5%6%9%44%
1651
August1st to 15thNight
11%5%244345%48%44%
1620
16th to endNight
11%435%5%33435%48%
1728
September1st to 15thNight
15%42442436%8%42%
1829
16th to endNight
15%6%35%42335%6%42%
1815
October1st to 15thNight
22%8%36%5%3435%5%31%
1971
16th to endNight
30%10%36%6%34345%20%
2139
November1st to 15thNight
18%13%46%6%25%5%45%26%
2363
16th to endNight
22%15%6%9%6%34346%17%
2520
December1st to 15thNight
20%23%8%11%7%343339%
2520
16th to endNight
21%20%12%13%6%233238%
2811

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
16%17%10%16%9%4432310%
1333
16th to endDay
11%19%9%16%11%5%5%3439%
1728
February1st to 15thDay
13%18%9%16%10%5%443310%
1575
16th to endDay
15%19%6%12%9%5%5%44312%
1488
March1st to 15thDay
15%12%5%10%8%4434423%
1948
16th to endDay
15%9%5%8%6%35%45%5%30%
2111
April1st to 15thDay
21%12%46%42445%5%28%
2146
16th to endDay
19%10%34323347%36%
2340
May1st to 15thDay
19%7%35%42345%6%36%
2337
16th to endDay
14%7%245%3445%7%39%
2618
June1st to 15thDay
17%7%35%4245%6%8%35%
2628
16th to endDay
17%5%25%5%25%5%6%8%36%
2700
July1st to 15thDay
13%5%35%435%5%5%8%38%
2700
16th to endDay
12%5%25%6%25%5%7%8%35%
2515
August1st to 15thDay
13%6%26%5%35%5%48%36%
2340
16th to endDay
13%6%25%6%45%5%5%8%35%
2462
September1st to 15thDay
18%8%36%5%24345%36%
2050
16th to endDay
18%8%24424448%37%
1815
October1st to 15thDay
24%9%27%5%23345%29%
1658
16th to endDay
32%15%47%5%25%33416%
1733
November1st to 15thDay
17%18%46%6%34346%24%
1495
16th to endDay
21%20%6%9%6%25%345%13%
1440
December1st to 15thDay
18%22%13%12%7%344246%
1440
16th to endDay
17%26%11%13%8%233237%
1410
January1st to 15thNight
19%17%9%15%10%443338%
2601
16th to endNight
12%17%10%15%12%46%33310%
2496
February1st to 15thNight
12%17%10%15%10%45%43213%
2278
16th to endNight
14%14%8%12%8%34436%18%
1982
March1st to 15thNight
16%13%6%9%8%25%44425%
2011
16th to endNight
15%9%5%8%43433437%
2112
April1st to 15thNight
20%12%35%5%23346%32%
1814
16th to endNight
16%10%35%6%34446%36%
1620
May1st to 15thNight
16%7%36%43435%7%36%
1613
16th to endNight
12%4335%345%5%8%42%
1495
June1st to 15thNight
15%6%16%6%2446%7%38%
1329
16th to endNight
13%42442446%8%43%
1260
July1st to 15thNight
10%32342345%8%51%
1260
16th to endNight
10%4245%25%47%9%44%
1651
August1st to 15thNight
11%5%243435%6%8%44%
1620
16th to endNight
11%426%5%24446%47%
1728
September1st to 15thNight
15%425%33435%7%43%
1829
16th to endNight
15%6%35%42435%6%42%
1815
October1st to 15thNight
21%8%36%5%24446%31%
1971
16th to endNight
29%12%36%6%34345%21%
2139
November1st to 15thNight
18%14%37%6%25%45%426%
2363
16th to endNight
22%16%6%8%6%34445%18%
2520
December1st to 15thNight
19%24%8%12%6%334329%
2520
16th to endNight
20%20%13%12%7%233338%
2811

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
80%5%5%6%1
1334
16th to endDay
78%48%5%2
1728
February1st to 15thDay
79%36%8%1
1577
16th to endDay
75%48%7%4
1488
March1st to 15thDay
64%410%12%7%
1948
16th to endDay
53%6%11%14%12%1
2112
April1st to 15thDay
56%49%19%9%
2146
16th to endDay
47%5%10%20%14%1
2340
May1st to 15thDay
47%6%9%22%13%
2337
16th to endDay
43%5%14%21%14%1
2622
June1st to 15thDay
45%6%12%22%13%
2628
16th to endDay
43%7%14%23%11%
2700
July1st to 15thDay
39%7%13%22%14%1
2541
16th to endDay
43%7%14%22%11%1
2358
August1st to 15thDay
44%7%14%19%12%1
2327
16th to endDay
44%8%14%22%9%1
2462
September1st to 15thDay
48%6%12%22%9%1
2050
16th to endDay
45%5%14%25%8%
1815
October1st to 15thDay
56%410%16%11%
1658
16th to endDay
71%5%10%8%3
1733
November1st to 15thDay
61%5%11%13%6%
1495
16th to endDay
72%5%10%8%1
1440
December1st to 15thDay
83%5%6%4
1440
16th to endDay
83%45%6%
1410
January1st to 15thNight
79%48%5%1
2601
16th to endNight
78%5%8%42
2496
February1st to 15thNight
76%5%8%8%1
2287
16th to endNight
67%411%9%6%
1982
March1st to 15thNight
62%5%9%15%6%
2011
16th to endNight
51%39%18%14%2
2112
April1st to 15thNight
54%49%18%12%
1814
16th to endNight
49%5%8%17%17%2
1620
May1st to 15thNight
47%49%22%13%2
1614
16th to endNight
38%6%12%26%12%2
1497
June1st to 15thNight
43%5%13%22%14%
1329
16th to endNight
36%7%13%25%15%
1260
July1st to 15thNight
29%5%12%28%22%1
1190
16th to endNight
35%7%14%23%16%1
1545
August1st to 15thNight
35%8%15%24%14%
1609
16th to endNight
37%6%12%28%13%1
1728
September1st to 15thNight
39%6%13%27%11%1
1829
16th to endNight
42%414%25%11%
1815
October1st to 15thNight
52%6%10%17%11%
1971
16th to endNight
66%6%11%11%4
2139
November1st to 15thNight
59%5%12%14%5%1
2363
16th to endNight
68%5%12%9%2
2520
December1st to 15thNight
80%6%8%31
2520
16th to endNight
81%5%7%5%
2811

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
19%29%39%9%1
71
16th to endDay
28%10%36%23%1
96
February1st to 15thDay
30%26%33%10%
90
16th to endDay
30%22%33%11%2
81
March1st to 15thDay
24%16%34%17%6%
238
16th to endDay
26%7%31%21%10%2
288
April1st to 15thDay
24%12%31%19%10%2
270
16th to endDay
27%10%24%20%10%7%
270
May1st to 15thDay
24%7%27%24%12%4
288
16th to endDay
19%9%29%20%16%4
331
June1st to 15thDay
18%10%27%25%15%2
423
16th to endDay
17%7%32%28%11%2
495
July1st to 15thDay
13%7%27%30%15%6%
475
16th to endDay
13%424%30%18%8%
346
August1st to 15thDay
15%222%26%19%13%
313
16th to endDay
17%317%27%20%13%
332
September1st to 15thDay
17%5%22%25%18%11%
299
16th to endDay
20%6%22%21%20%9%
254
October1st to 15thDay
23%7%27%28%9%3
255
16th to endDay
42%12%22%19%3
245
November1st to 15thDay
24%9%32%24%8%2
75
16th to endDay
33%16%31%13%5%
60
December1st to 15thDay
35%28%23%11%1
60
16th to endDay
37%26%35%
64
January1st to 15thNight
26%18%33%15%4
885
16th to endNight
20%12%34%26%5%
768
February1st to 15thNight
21%14%37%21%4
704
16th to endNight
21%13%34%25%4
631
March1st to 15thNight
20%16%35%20%5%
720
16th to endNight
20%10%30%27%10%1
768
April1st to 15thNight
26%11%31%23%6%
679
16th to endNight
22%11%27%27%10%1
540
May1st to 15thNight
21%6%25%32%12%1
534
16th to endNight
14%430%34%15%
375
June1st to 15thNight
17%5%28%36%11%
360
16th to endNight
15%326%38%14%
360
July1st to 15thNight
10%220%47%18%
340
16th to endNight
11%222%39%21%1
535
August1st to 15thNight
13%216%39%26%1
539
16th to endNight
13%319%34%25%3
582
September1st to 15thNight
19%322%30%18%5%
707
16th to endNight
19%420%34%16%4
657
October1st to 15thNight
25%7%26%27%11%1
660
16th to endNight
34%11%27%21%3
704
November1st to 15thNight
25%11%32%20%8%1
700
16th to endNight
29%15%29%20%5%
720
December1st to 15thNight
31%18%31%15%2
720
16th to endNight
29%16%36%14%2
891
Page generated at 2017-09-13 07:39:17. Version ac04

Copyright 2017 A. Danko


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