Monmouth
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Monmouth clear sky chart from 2005-11-06 to 2024-03-08.

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%
22866
13%
80772
13%
22770
49%
22770
17%
57466

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
25%
754
4%
4403
5%
736
28%
736
4%
3890
January11th to 20thNight
30%
758
7%
4404
8%
740
33%
740
5%
3649
January21st to endNight
36%
834
7%
4513
12%
814
39%
814
6%
3800
February1st to 10thNight
34%
760
7%
2470
7%
760
36%
760
10%
2039
February11th to 20thNight
35%
740
9%
2404
7%
740
39%
740
13%
1870
February21st to endNight
32%
628
10%
1979
8%
628
35%
628
11%
1553
March1st to 10thNight
36%
750
10%
2124
7%
750
38%
750
14%
1685
March11th to 20thNight
40%
720
12%
1980
9%
720
42%
720
15%
1549
March21st to endNight
33%
792
6%
2155
4%
792
34%
792
12%
1765
April1st to 10thNight
36%
720
8%
1800
4%
720
38%
720
15%
1434
April11th to 20thNight
40%
703
11%
1771
5%
703
42%
703
21%
1302
April21st to endNight
43%
540
11%
1620
7%
540
46%
540
19%
1145
May1st to 10thNight
47%
443
14%
1523
11%
443
53%
443
24%
961
May11th to 20thNight
53%
354
13%
1416
16%
354
56%
354
18%
902
May21st to endNight
50%
389
10%
1552
12%
388
55%
388
18%
984
June1st to 10thNight
52%
360
10%
1440
14%
360
55%
360
20%
889
June11th to 20thNight
50%
360
10%
1440
13%
360
56%
360
23%
848
June21st to endNight
60%
360
17%
1440
21%
360
69%
360
38%
677
July1st to 10thNight
77%
350
19%
1400
29%
350
81%
350
47%
590
July11th to 20thNight
67%
348
27%
1392
32%
348
79%
348
51%
543
July21st to endNight
81%
424
33%
1517
40%
401
88%
401
74%
493
August1st to 10thNight
83%
537
27%
1602
25%
534
86%
534
62%
706
August11th to 20thNight
83%
534
32%
1602
26%
534
86%
534
59%
724
August21st to endNight
70%
707
35%
1895
22%
707
74%
707
55%
970
September1st to 10thNight
69%
720
31%
1800
18%
720
72%
720
58%
953
September11th to 20thNight
67%
720
25%
1822
17%
720
69%
720
41%
1116
September21st to endNight
64%
720
24%
2052
21%
720
66%
720
38%
1216
October1st to 10thNight
54%
720
16%
2160
15%
720
58%
720
31%
1340
October11th to 20thNight
55%
720
19%
2160
21%
720
57%
720
26%
1423
October21st to endNight
41%
792
17%
2380
14%
792
46%
792
21%
1665
November1st to 10thNight
39%
740
10%
2512
10%
740
41%
740
13%
1917
November11th to 20thNight
34%
760
8%
2660
7%
760
37%
760
10%
2118
November21st to endNight
38%
760
8%
2660
6%
760
42%
760
13%
1987
December1st to 10thNight
38%
760
10%
2660
10%
760
39%
760
12%
2034
December11th to 20thNight
28%
759
6%
3222
7%
759
28%
759
6%
2660
December21st to endNight
25%
830
3%
4842
5%
817
27%
817
4%
4069

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%47%6%35%45%6%34%
78533
Night
19%9%47%6%3445%6%34%
81054
TransparencyDay
51%7%12%17%11%3
78238
Night
51%7%12%17%10%3
80870
SeeingDay
17%10%22%27%19%5%
13761
Night
19%7%19%34%19%2
22887

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
29%16%8%14%8%444337%
2539
11th to 20thDay
36%12%5%10%7%3433413%
2540
21st to endDay
26%13%6%10%9%45%5%45%13%
3146
February1st to 10thDay
26%11%5%10%8%47%45%5%15%
1710
11th to 20thDay
26%12%49%7%45%5%5%418%
1665
21st to endDay
24%14%410%7%45%435%18%
1475
March1st to 10thDay
24%12%5%9%7%46%5%6%6%17%
1992
11th to 20thDay
24%13%48%7%45%446%21%
1980
21st to endDay
25%12%5%9%9%46%5%46%16%
2200
April1st to 10thDay
23%12%5%11%8%446%5%6%18%
2160
11th to 20thDay
23%10%47%6%46%45%5%25%
2135
21st to endDay
19%9%36%6%5%6%5%6%8%27%
2340
May1st to 10thDay
14%8%46%6%46%5%6%7%35%
2434
11th to 20thDay
18%8%37%6%35%45%8%32%
2477
21st to endDay
18%7%36%6%45%6%6%8%32%
2723
June1st to 10thDay
19%7%48%5%35%45%6%34%
2520
11th to 20thDay
15%7%46%6%36%6%6%8%32%
2520
21st to endDay
8%5%24435%45%6%56%
2520
July1st to 10thDay
5%323433447%62%
2520
11th to 20thDay
5%323323345%67%
2520
21st to endDay
431221222476%
2708
August1st to 10thDay
3213424347%67%
2328
11th to 20thDay
431332335%6%68%
2298
21st to endDay
432443345%8%61%
2459
September1st to 10thDay
6%313322346%67%
2160
11th to 20thDay
9%7%27%6%25%45%7%46%
2134
21st to endDay
14%6%25%5%3445%5%46%
1908
October1st to 10thDay
15%7%36%5%35%5%5%7%40%
1800
11th to 20thDay
16%9%5%9%7%445%5%6%31%
1800
21st to endDay
20%13%49%5%5%4346%28%
1976
November1st to 10thDay
24%15%5%9%7%36%5%5%5%15%
1564
11th to 20thDay
28%10%6%8%8%45%5%45%18%
1520
21st to endDay
24%11%49%6%36%45%6%21%
1520
December1st to 10thDay
24%12%6%9%7%34345%21%
1520
11th to 20thDay
24%11%6%11%7%45%8%6%7%11%
1928
21st to endDay
28%15%7%17%9%35%3336%
2794
January1st to 10thNight
29%18%7%9%7%3443411%
4406
11th to 20thNight
32%15%5%8%6%3434416%
4417
21st to endNight
31%13%5%9%7%44435%15%
4521
February1st to 10thNight
21%14%49%7%45%5%5%6%19%
2470
11th to 20thNight
24%11%47%6%35%5%45%26%
2402
21st to endNight
23%11%5%8%6%345%5%6%23%
1979
March1st to 10thNight
19%11%49%7%45%5%5%6%24%
2124
11th to 20thNight
21%9%47%6%35%5%7%7%25%
1980
21st to endNight
23%10%49%7%36%45%6%22%
2155
April1st to 10thNight
23%11%48%6%4445%6%26%
1800
11th to 20thNight
18%8%47%5%3445%7%34%
1771
21st to endNight
16%7%47%6%346%5%7%35%
1620
May1st to 10thNight
10%7%38%5%3445%6%45%
1523
11th to 20thNight
13%7%45%6%5%5%46%7%38%
1416
21st to endNight
13%6%45%5%335%7%9%39%
1552
June1st to 10thNight
15%6%35%6%35%45%7%43%
1440
11th to 20thNight
13%5%36%4245%5%6%47%
1440
21st to endNight
5%5%24422445%64%
1440
July1st to 10thNight
3213313335%72%
1440
11th to 20thNight
4312212335%73%
1440
21st to endNight
3111213384%
1606
August1st to 10thNight
2212212346%74%
1611
11th to 20thNight
3312123335%76%
1602
21st to endNight
5%223312345%70%
1895
September1st to 10thNight
421332234471%
1800
11th to 20thNight
8%5%245%3446%6%54%
1822
21st to endNight
9%42443436%7%54%
2052
October1st to 10thNight
13%6%25%5%34447%48%
2160
11th to 20thNight
15%5%36%5%345%5%7%42%
2160
21st to endNight
19%9%36%5%3445%6%38%
2380
November1st to 10thNight
22%8%47%7%45%5%5%7%26%
2512
11th to 20thNight
27%10%47%7%36%5%5%5%22%
2660
21st to endNight
21%7%49%8%45%446%28%
2660
December1st to 10thNight
24%9%47%6%35%45%5%25%
2660
11th to 20thNight
24%11%49%9%5%5%45%6%17%
3276
21st to endNight
24%12%6%13%8%5%5%5%5%5%13%
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
83%6%6%311
2539
11th to 20thDay
76%5%6%8%31
2540
21st to endDay
72%9%7%7%5%
3146
February1st to 10thDay
70%8%8%10%4
1710
11th to 20thDay
68%9%8%9%41
1674
21st to endDay
69%7%8%9%5%1
1475
March1st to 10thDay
66%8%12%10%4
1992
11th to 20thDay
64%7%11%12%6%1
1980
21st to endDay
70%9%11%9%1
2200
April1st to 10thDay
67%7%11%11%3
2160
11th to 20thDay
60%7%11%13%6%3
2138
21st to endDay
56%9%14%13%7%1
2340
May1st to 10thDay
47%8%16%19%10%
2434
11th to 20thDay
51%8%14%18%8%1
2480
21st to endDay
50%10%17%18%4
2724
June1st to 10thDay
51%7%18%19%5%1
2520
11th to 20thDay
48%9%22%16%5%
2520
21st to endDay
30%6%19%29%12%4
2520
July1st to 10thDay
22%6%15%28%22%7%
2451
11th to 20thDay
20%410%27%31%8%
2445
21st to endDay
13%29%32%36%8%
2557
August1st to 10thDay
18%5%16%33%22%6%
2312
11th to 20thDay
18%5%14%33%24%6%
2298
21st to endDay
23%6%12%31%24%4
2459
September1st to 10thDay
19%5%13%30%21%12%
2160
11th to 20thDay
37%8%12%21%16%6%
2134
21st to endDay
39%7%13%21%15%6%
1908
October1st to 10thDay
44%7%11%18%16%4
1800
11th to 20thDay
53%8%12%14%12%2
1800
21st to endDay
59%7%8%12%13%1
1976
November1st to 10thDay
69%8%8%10%4
1564
11th to 20thDay
68%6%10%8%5%1
1520
21st to endDay
64%8%8%8%11%1
1520
December1st to 10thDay
66%6%8%11%9%1
1520
11th to 20thDay
70%11%9%8%2
1928
21st to endDay
81%7%6%32
2794
January1st to 10thNight
77%7%7%431
4406
11th to 20thNight
73%5%7%10%41
4417
21st to endNight
72%6%8%8%6%1
4521
February1st to 10thNight
65%8%10%12%4
2470
11th to 20thNight
60%7%13%12%6%2
2404
21st to endNight
62%7%12%11%6%2
1979
March1st to 10thNight
60%8%12%14%6%
2124
11th to 20thNight
56%9%12%15%6%1
1980
21st to endNight
63%9%14%13%2
2155
April1st to 10thNight
59%8%15%12%6%
1800
11th to 20thNight
51%6%19%15%6%3
1771
21st to endNight
49%7%17%18%7%2
1620
May1st to 10thNight
39%8%17%25%8%2
1523
11th to 20thNight
44%8%17%22%6%3
1416
21st to endNight
41%11%21%22%5%
1552
June1st to 10thNight
42%7%18%27%5%1
1440
11th to 20thNight
37%8%24%25%7%
1440
21st to endNight
24%6%21%33%13%4
1440
July1st to 10thNight
17%6%15%30%25%7%
1400
11th to 20thNight
15%414%27%32%9%
1392
21st to endNight
7%210%35%36%11%
1517
August1st to 10thNight
12%417%38%22%7%
1602
11th to 20thNight
14%414%38%22%8%
1602
21st to endNight
18%5%11%38%23%6%
1895
September1st to 10thNight
17%5%14%31%22%12%
1800
11th to 20thNight
29%7%16%23%16%9%
1822
21st to endNight
30%6%17%20%18%8%
2052
October1st to 10thNight
37%6%11%25%18%4
2160
11th to 20thNight
40%8%14%19%15%4
2160
21st to endNight
47%8%12%15%16%2
2380
November1st to 10thNight
57%9%12%15%6%
2512
11th to 20thNight
64%7%10%9%7%2
2660
21st to endNight
57%7%10%11%13%2
2660
December1st to 10thNight
60%7%11%12%10%1
2660
11th to 20thNight
67%9%10%10%4
3276
21st to endNight
69%10%10%7%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
38%14%21%17%7%3
180
11th to 20thDay
31%14%22%19%11%3
180
21st to endDay
25%14%22%22%13%5%
407
February1st to 10thDay
30%14%19%21%12%4
370
11th to 20thDay
29%13%29%17%10%2
365
21st to endDay
26%21%22%19%10%1
337
March1st to 10thDay
27%13%30%20%10%1
449
11th to 20thDay
26%14%22%23%13%2
420
21st to endDay
27%15%25%22%10%2
462
April1st to 10thDay
28%17%20%21%11%4
420
11th to 20thDay
26%17%25%19%9%5%
412
21st to endDay
20%15%29%20%15%2
420
May1st to 10thDay
17%13%24%27%16%4
423
11th to 20thDay
22%12%21%23%18%5%
448
21st to endDay
12%10%21%28%21%7%
485
June1st to 10thDay
16%9%24%26%22%3
450
11th to 20thDay
15%10%25%34%14%2
450
21st to endDay
6%6%19%35%27%6%
450
July1st to 10thDay
6%418%38%26%8%
446
11th to 20thDay
2422%37%27%7%
444
21st to endDay
3315%37%34%8%
487
August1st to 10thDay
3216%33%34%11%
447
11th to 20thDay
2211%37%36%12%
437
21st to endDay
4419%37%30%7%
495
September1st to 10thDay
7%425%31%27%7%
450
11th to 20thDay
10%6%19%30%27%8%
450
21st to endDay
12%9%22%32%18%6%
450
October1st to 10thDay
16%9%22%26%21%7%
450
11th to 20thDay
18%9%17%27%23%6%
450
21st to endDay
23%13%24%22%14%5%
491
November1st to 10thDay
23%15%29%20%11%2
218
11th to 20thDay
21%15%27%17%18%3
180
21st to endDay
25%17%18%17%19%3
180
December1st to 10thDay
29%14%14%25%14%4
180
11th to 20thDay
33%13%23%22%6%3
180
21st to endDay
30%17%18%23%10%2
198
January1st to 10thNight
34%10%21%22%11%2
760
11th to 20thNight
30%11%17%22%17%2
760
21st to endNight
26%7%17%32%15%3
836
February1st to 10thNight
23%10%21%28%16%1
760
11th to 20thNight
25%10%21%27%15%
744
21st to endNight
26%13%22%28%12%
628
March1st to 10thNight
22%9%24%31%14%1
750
11th to 20thNight
21%11%19%33%14%1
720
21st to endNight
24%10%23%29%13%1
792
April1st to 10thNight
26%8%21%28%17%1
720
11th to 20thNight
20%8%25%31%15%1
703
21st to endNight
18%6%22%37%17%1
540
May1st to 10thNight
11%7%25%38%17%2
443
11th to 20thNight
14%5%19%42%20%1
354
21st to endNight
15%5%20%37%22%1
389
June1st to 10thNight
14%420%42%20%
360
11th to 20thNight
12%330%42%13%1
360
21st to endNight
7%223%51%17%
360
July1st to 10thNight
4212%58%24%1
350
11th to 20thNight
5%222%51%20%
348
21st to endNight
2114%53%29%
424
August1st to 10thNight
318%47%36%4
537
11th to 20thNight
418%45%40%2
534
21st to endNight
5%217%46%29%1
707
September1st to 10thNight
5%219%44%29%1
720
11th to 20thNight
8%313%36%34%5%
720
21st to endNight
9%417%41%26%3
720
October1st to 10thNight
14%223%34%24%3
720
11th to 20thNight
17%415%35%23%5%
720
21st to endNight
22%7%22%28%17%4
792
November1st to 10thNight
23%7%21%32%16%1
740
11th to 20thNight
28%11%20%26%14%1
760
21st to endNight
23%6%19%31%18%2
760
December1st to 10thNight
27%7%18%30%16%3
760
11th to 20thNight
30%10%22%23%14%1
760
21st to endNight
31%13%20%25%10%1
836
Page generated at 2024-03-05 04:24:00. Version ac07

Copyright © 2024 Attilla Danko.


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