Dixon Lomax Memorial Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dixon Lomax Memorial Observing Site clear sky chart from 2005-11-06 to 2024-03-18.

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
46%
24206
23%
79817
15%
24105
55%
24105
26%
48687

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
27%
753
27%
3978
11%
737
45%
737
15%
2132
January11th to 20thNight
30%
758
30%
3916
11%
740
46%
740
16%
2061
January21st to endNight
25%
829
19%
4445
10%
814
46%
814
14%
2668
February1st to 10thNight
36%
760
28%
2307
15%
760
49%
760
29%
1385
February11th to 20thNight
24%
743
24%
2218
8%
739
40%
739
23%
1430
February21st to endNight
26%
628
22%
1884
11%
628
38%
628
23%
1226
March1st to 10thNight
34%
760
27%
2171
14%
760
45%
760
29%
1329
March11th to 20thNight
32%
752
23%
2068
9%
752
43%
752
28%
1314
March21st to endNight
34%
792
22%
2178
10%
792
43%
792
25%
1409
April1st to 10thNight
39%
720
25%
1980
13%
720
48%
720
33%
1179
April11th to 20thNight
46%
576
26%
1779
16%
576
56%
576
30%
1044
April21st to endNight
54%
540
29%
1620
20%
540
61%
540
35%
935
May1st to 10thNight
50%
540
21%
1620
9%
540
59%
540
32%
966
May11th to 20thNight
51%
531
15%
1593
9%
531
54%
531
26%
1038
May21st to endNight
60%
582
18%
1744
13%
582
62%
582
27%
1124
June1st to 10thNight
59%
540
16%
1620
12%
540
61%
540
25%
1062
June11th to 20thNight
68%
540
16%
1620
14%
540
70%
540
34%
993
June21st to endNight
71%
540
15%
1620
13%
540
72%
540
32%
1015
July1st to 10thNight
64%
525
11%
1575
9%
525
64%
525
23%
1094
July11th to 20thNight
69%
522
11%
1566
9%
522
70%
522
23%
1066
July21st to endNight
67%
591
15%
1672
12%
558
68%
558
26%
1112
August1st to 10thNight
65%
537
13%
1600
12%
534
66%
534
25%
1078
August11th to 20thNight
61%
534
19%
1606
17%
534
63%
534
23%
1118
August21st to endNight
63%
614
17%
2000
18%
614
63%
614
23%
1328
September1st to 10thNight
61%
720
18%
1980
15%
720
62%
720
28%
1326
September11th to 20thNight
56%
720
21%
1980
16%
720
59%
720
27%
1317
September21st to endNight
58%
720
26%
1980
19%
720
63%
720
32%
1239
October1st to 10thNight
55%
720
29%
1980
22%
720
61%
720
35%
1197
October11th to 20thNight
52%
720
30%
2145
24%
720
60%
720
33%
1258
October21st to endNight
53%
792
33%
2376
25%
792
66%
792
37%
1314
November1st to 10thNight
52%
740
29%
2332
24%
740
62%
740
35%
1293
November11th to 20thNight
42%
760
29%
2470
20%
760
56%
760
31%
1394
November21st to endNight
43%
760
27%
2470
19%
760
56%
760
28%
1464
December1st to 10thNight
34%
760
25%
2470
14%
760
49%
760
22%
1572
December11th to 20thNight
37%
759
30%
2887
18%
758
51%
758
26%
1584
December21st to endNight
32%
828
16%
4367
13%
817
44%
817
13%
2623

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
15%5%245%35%5%6%7%43%
79033
Night
16%5%2443445%7%45%
80767
TransparencyDay
40%411%20%19%6%
78756
Night
40%310%20%21%6%
80563
SeeingDay
20%8%22%24%17%9%
14067
Night
18%6%20%30%20%5%
24233

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
18%42332346%6%48%
2836
11th to 20thDay
16%5%2443333453%
2840
21st to endDay
27%41332343447%
3124
February1st to 10thDay
17%6%25%5%2445%6%44%
1871
11th to 20thDay
21%6%2442345%7%43%
1848
21st to endDay
21%5%25%5%3434443%
1570
March1st to 10thDay
18%423424347%49%
2007
11th to 20thDay
20%5%344345%5%6%42%
2058
21st to endDay
19%5%25%5%45%45%6%40%
2178
April1st to 10thDay
13%324435%6%5%8%47%
1980
11th to 20thDay
15%4245%3445%7%46%
2144
21st to endDay
12%32443446%7%51%
2340
May1st to 10thDay
11%5%35%5%345%5%8%46%
2340
11th to 20thDay
15%5%25%6%46%6%6%8%37%
2301
21st to endDay
13%425%6%45%6%7%10%38%
2531
June1st to 10thDay
12%6%25%6%47%6%8%11%33%
2340
11th to 20thDay
7%425%6%46%8%8%12%39%
2340
21st to endDay
8%425%6%47%8%7%12%37%
2340
July1st to 10thDay
9%5%37%7%5%8%8%9%10%29%
2340
11th to 20thDay
10%436%8%48%8%9%10%29%
2340
21st to endDay
7%435%7%7%8%8%8%11%32%
2547
August1st to 10thDay
12%5%26%6%5%7%9%8%9%31%
2327
11th to 20thDay
12%5%36%7%5%6%6%7%11%33%
2291
21st to endDay
13%5%26%6%46%7%8%9%32%
2336
September1st to 10thDay
11%5%26%7%46%6%7%8%38%
1980
11th to 20thDay
17%5%25%5%45%6%7%8%39%
1980
21st to endDay
16%5%24435%447%47%
1980
October1st to 10thDay
16%413323346%55%
1980
11th to 20thDay
14%5%14322445%57%
1814
21st to endDay
15%41332334458%
1980
November1st to 10thDay
14%313322335%59%
1743
11th to 20thDay
16%41332335%5%54%
1710
21st to endDay
17%42442345%6%50%
1710
December1st to 10thDay
24%6%2443435%5%40%
1710
11th to 20thDay
18%42332345%5%50%
2153
21st to endDay
24%5%2332335%7%44%
3124
January1st to 10thNight
19%424433336%49%
4109
11th to 20thNight
15%6%245%33346%49%
4120
21st to endNight
27%5%2432333444%
4532
February1st to 10thNight
16%5%1442445%6%49%
2307
11th to 20thNight
22%5%24433345%44%
2218
21st to endNight
20%5%24435%45%6%41%
1884
March1st to 10thNight
16%5%24423446%49%
2171
11th to 20thNight
16%5%244345%6%6%44%
2068
21st to endNight
18%5%35%43445%6%44%
2178
April1st to 10thNight
14%32432445%7%52%
1980
11th to 20thNight
13%5%24424447%50%
1779
21st to endNight
12%42442445%7%52%
1620
May1st to 10thNight
11%425%425%5%6%7%47%
1620
11th to 20thNight
15%6%45%5%35%5%5%8%39%
1592
21st to endNight
13%5%36%6%35%5%6%8%41%
1744
June1st to 10thNight
11%6%26%7%46%7%7%9%36%
1620
11th to 20thNight
8%4245%45%6%6%11%44%
1620
21st to endNight
8%325%5%35%8%7%11%42%
1620
July1st to 10thNight
12%6%37%7%46%6%7%12%30%
1620
11th to 20thNight
11%426%7%5%7%8%8%12%31%
1620
21st to endNight
7%5%37%7%37%8%8%12%33%
1771
August1st to 10thNight
13%5%25%5%46%7%9%10%33%
1611
11th to 20thNight
15%6%36%6%36%6%6%11%33%
1606
21st to endNight
13%6%35%6%5%6%6%7%10%34%
2000
September1st to 10thNight
12%6%37%6%45%5%7%9%38%
1980
11th to 20thNight
17%6%26%5%345%6%7%39%
1980
21st to endNight
15%425%5%335%47%47%
1980
October1st to 10thNight
16%413423445%54%
1980
11th to 20thNight
15%425%423345%53%
2145
21st to endNight
15%413323345%58%
2376
November1st to 10thNight
14%42432333458%
2332
11th to 20thNight
17%423423345%53%
2470
21st to endNight
18%5%2333445%6%47%
2470
December1st to 10thNight
22%6%25%434346%43%
2470
11th to 20thNight
17%5%24312345%54%
3042
21st to endNight
24%5%2442445%7%38%
4532

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%1422%25%10%
2837
11th to 20thDay
38%15%15%30%9%
2840
21st to endDay
45%1319%22%11%
3124
February1st to 10thDay
41%37%21%21%7%
1871
11th to 20thDay
42%37%18%23%7%
1858
21st to endDay
46%27%15%20%10%
1570
March1st to 10thDay
38%27%19%23%11%
2007
11th to 20thDay
44%39%18%18%9%
2058
21st to endDay
45%39%21%19%3
2178
April1st to 10thDay
36%39%22%24%6%
1980
11th to 20thDay
39%37%19%24%8%
2144
21st to endDay
34%39%29%21%4
2340
May1st to 10thDay
38%412%21%20%5%
2340
11th to 20thDay
45%416%20%13%2
2305
21st to endDay
42%5%13%23%16%2
2531
June1st to 10thDay
44%5%16%24%9%2
2340
11th to 20thDay
37%6%21%22%12%2
2340
21st to endDay
38%8%17%21%13%3
2340
July1st to 10thDay
47%7%18%18%9%2
2275
11th to 20thDay
46%7%21%16%7%4
2271
21st to endDay
43%7%21%19%9%
2405
August1st to 10thDay
45%7%17%23%7%1
2314
11th to 20thDay
44%7%18%21%8%2
2291
21st to endDay
44%7%17%20%10%2
2336
September1st to 10thDay
43%5%14%18%17%4
1980
11th to 20thDay
43%5%11%19%20%3
1980
21st to endDay
39%39%21%20%7%
1980
October1st to 10thDay
33%39%20%29%7%
1980
11th to 20thDay
32%27%23%24%11%
1814
21st to endDay
32%25%20%29%13%
1980
November1st to 10thDay
31%27%19%29%13%
1743
11th to 20thDay
33%25%21%28%10%
1710
21st to endDay
36%26%20%28%8%
1710
December1st to 10thDay
48%35%19%18%7%
1710
11th to 20thDay
38%16%19%23%13%
2150
21st to endDay
43%15%21%26%4
3124
January1st to 10thNight
41%1417%29%8%
4109
11th to 20thNight
39%25%17%28%10%
4120
21st to endNight
48%1415%25%9%
4532
February1st to 10thNight
38%37%23%22%7%
2307
11th to 20thNight
44%2419%23%7%
2219
21st to endNight
45%27%16%21%8%
1884
March1st to 10thNight
39%27%19%22%12%
2171
11th to 20thNight
40%312%17%22%7%
2068
21st to endNight
43%28%21%21%4
2178
April1st to 10thNight
34%39%22%26%6%
1980
11th to 20thNight
36%26%22%24%10%
1779
21st to endNight
33%310%28%22%4
1620
May1st to 10thNight
36%314%23%21%3
1620
11th to 20thNight
43%415%21%15%1
1593
21st to endNight
42%5%12%26%13%2
1745
June1st to 10thNight
43%6%16%23%11%2
1620
11th to 20thNight
34%6%21%24%13%1
1620
21st to endNight
33%9%20%20%13%5%
1620
July1st to 10thNight
47%6%21%17%9%1
1575
11th to 20thNight
43%9%24%15%7%2
1566
21st to endNight
40%9%22%21%7%2
1672
August1st to 10thNight
43%7%21%21%8%
1600
11th to 20thNight
45%8%15%18%12%1
1606
21st to endNight
45%6%17%21%8%3
2000
September1st to 10thNight
41%7%13%20%14%4
1980
11th to 20thNight
44%414%19%18%2
1980
21st to endNight
39%310%21%22%7%
1980
October1st to 10thNight
35%410%18%28%6%
1980
11th to 20thNight
36%27%22%23%10%
2145
21st to endNight
31%2422%29%12%
2376
November1st to 10thNight
32%27%19%27%12%
2332
11th to 20thNight
36%1417%29%12%
2470
21st to endNight
38%35%22%25%7%
2470
December1st to 10thNight
45%27%19%20%7%
2470
11th to 20thNight
36%27%18%28%10%
3044
21st to endNight
48%15%20%21%5%
4532

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
28%16%39%13%31
270
11th to 20thDay
31%17%31%16%41
270
21st to endDay
30%18%36%12%31
297
February1st to 10thDay
24%17%39%17%4
270
11th to 20thDay
36%17%34%12%1
270
21st to endDay
36%19%34%10%1
225
March1st to 10thDay
27%13%32%21%7%
377
11th to 20thDay
27%13%33%21%6%1
449
21st to endDay
28%13%29%22%8%1
462
April1st to 10thDay
23%11%27%27%10%2
420
11th to 20thDay
17%13%33%22%12%2
412
21st to endDay
19%9%25%26%16%5%
420
May1st to 10thDay
17%10%30%24%12%8%
423
11th to 20thDay
21%419%25%21%11%
447
21st to endDay
17%6%16%25%21%14%
485
June1st to 10thDay
16%414%30%22%14%
450
11th to 20thDay
10%5%14%28%25%19%
450
21st to endDay
11%318%32%21%15%
450
July1st to 10thDay
12%29%25%28%22%
445
11th to 20thDay
8%310%26%29%25%
444
21st to endDay
5%18%30%32%24%
488
August1st to 10thDay
18%412%19%26%22%
446
11th to 20thDay
12%37%25%35%18%
439
21st to endDay
17%48%25%28%18%
495
September1st to 10thDay
12%212%26%33%15%
450
11th to 20thDay
18%411%24%32%12%
450
21st to endDay
19%315%29%26%8%
450
October1st to 10thDay
21%419%28%19%10%
450
11th to 20thDay
18%6%23%32%18%4
450
21st to endDay
21%6%26%29%15%4
495
November1st to 10thDay
22%5%29%26%13%4
341
11th to 20thDay
21%17%33%24%6%
270
21st to endDay
17%9%39%25%9%2
270
December1st to 10thDay
31%13%31%21%41
270
11th to 20thDay
26%11%38%18%6%1
270
21st to endDay
35%12%30%17%42
297
January1st to 10thNight
24%11%31%26%7%
760
11th to 20thNight
23%10%31%29%7%
760
21st to endNight
23%11%35%28%4
836
February1st to 10thNight
21%9%30%35%5%
760
11th to 20thNight
26%13%32%26%3
743
21st to endNight
24%12%34%27%3
628
March1st to 10thNight
21%10%30%34%5%
760
11th to 20thNight
20%9%34%27%9%1
752
21st to endNight
21%11%27%31%10%1
792
April1st to 10thNight
17%11%28%33%10%1
720
11th to 20thNight
17%9%23%34%16%1
576
21st to endNight
14%5%21%37%20%3
540
May1st to 10thNight
14%5%23%33%24%1
540
11th to 20thNight
19%317%32%24%6%
531
21st to endNight
15%310%27%34%11%
584
June1st to 10thNight
14%211%32%33%8%
540
11th to 20thNight
10%110%31%31%16%
540
21st to endNight
8%29%33%39%10%
540
July1st to 10thNight
14%35%22%42%14%
525
11th to 20thNight
12%3422%41%17%
522
21st to endNight
8%16%24%46%14%
591
August1st to 10thNight
17%1421%42%14%
537
11th to 20thNight
16%35%25%40%11%
534
21st to endNight
14%45%25%39%13%
614
September1st to 10thNight
13%29%27%39%10%
720
11th to 20thNight
19%311%25%36%7%
720
21st to endNight
16%312%35%31%4
720
October1st to 10thNight
18%5%16%28%26%7%
720
11th to 20thNight
17%5%20%35%20%4
720
21st to endNight
17%6%19%36%18%3
792
November1st to 10thNight
17%6%19%35%20%3
740
11th to 20thNight
19%8%25%33%13%2
760
21st to endNight
21%6%26%34%13%1
760
December1st to 10thNight
27%8%24%33%8%1
760
11th to 20thNight
22%7%28%34%10%1
760
21st to endNight
30%8%23%33%6%
836
Page generated at 2024-03-15 14:01:46. Version ac07

Copyright © 2024 Attilla Danko.


Dixon Lomax Memorial Observing Site Clear Sky Chart |Charts Home