Huntingdon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Huntingdon clear sky chart from 2005-11-06 to 2024-01-22.

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
25%
22629
12%
74865
7%
22589
32%
22589
14%
55162

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
11%
760
7%
2649
1%
757
18%
757
6%
2196
January11th to 20thNight
12%
760
7%
2660
3%
760
18%
760
6%
2178
January21st to endNight
16%
800
10%
2798
5%
800
24%
800
10%
2132
February1st to 10thNight
12%
720
7%
2340
1%
720
19%
720
7%
1938
February11th to 20thNight
14%
703
11%
2190
4%
700
23%
700
11%
1677
February21st to endNight
17%
592
13%
1776
4%
592
28%
592
12%
1351
March1st to 10thNight
17%
720
12%
2160
7%
720
25%
720
11%
1678
March11th to 20thNight
18%
720
14%
2068
5%
720
27%
720
14%
1553
March21st to endNight
27%
792
18%
1998
8%
792
34%
792
19%
1488
April1st to 10thNight
20%
720
14%
1800
3%
720
25%
720
16%
1395
April11th to 20thNight
24%
711
13%
1775
3%
711
29%
711
19%
1342
April21st to endNight
24%
604
16%
1684
6%
604
31%
604
18%
1242
May1st to 10thNight
29%
401
15%
1481
12%
401
37%
401
14%
1031
May11th to 20thNight
31%
354
19%
1416
14%
354
46%
354
16%
901
May21st to endNight
34%
388
13%
1551
10%
388
44%
388
19%
964
June1st to 10thNight
29%
360
10%
1440
8%
360
39%
360
14%
994
June11th to 20thNight
36%
360
12%
1440
13%
360
45%
360
18%
904
June21st to endNight
34%
360
11%
1440
11%
360
44%
360
16%
942
July1st to 10thNight
44%
350
14%
1400
16%
350
54%
350
23%
826
July11th to 20thNight
46%
348
14%
1392
16%
348
54%
348
22%
812
July21st to endNight
43%
394
15%
1486
14%
372
49%
372
22%
891
August1st to 10thNight
50%
358
17%
1422
16%
356
58%
356
23%
855
August11th to 20thNight
47%
564
17%
1628
10%
564
51%
564
27%
1086
August21st to endNight
42%
792
17%
1980
7%
792
46%
792
30%
1354
September1st to 10thNight
43%
720
14%
1800
6%
720
46%
720
28%
1236
September11th to 20thNight
46%
720
20%
1859
12%
720
50%
720
31%
1207
September21st to endNight
39%
720
20%
1980
13%
720
43%
720
25%
1337
October1st to 10thNight
29%
720
16%
2120
10%
720
36%
720
18%
1512
October11th to 20thNight
27%
720
14%
2173
8%
720
34%
720
15%
1591
October21st to endNight
19%
792
10%
2574
6%
792
26%
792
11%
1986
November1st to 10thNight
23%
740
13%
2407
7%
740
32%
740
13%
1752
November11th to 20thNight
20%
760
14%
2550
9%
760
28%
760
12%
1864
November21st to endNight
17%
760
9%
2660
5%
760
23%
760
7%
2098
December1st to 10thNight
13%
760
6%
2660
2%
760
17%
760
5%
2234
December11th to 20thNight
11%
760
9%
3252
3%
759
18%
759
5%
2608
December21st to endNight
9%
826
3%
4856
1%
817
14%
817
3%
4007

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%10%47%6%35%45%6%31%
74830
Night
19%11%48%6%3445%6%29%
75100
TransparencyDay
52%7%12%19%10%1
74535
Night
55%6%11%17%9%1
74929
SeeingDay
22%16%29%21%9%2
13492
Night
23%16%29%23%8%1
22640

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 10thDay
18%19%7%11%8%46%43417%
1517
11th to 20thDay
17%19%8%10%9%35%44418%
1520
21st to endDay
12%15%7%11%8%46%5%5%6%21%
1592
February1st to 10thDay
16%17%6%12%8%45%45%5%19%
1616
11th to 20thDay
14%14%412%8%45%5%5%5%24%
1656
21st to endDay
18%16%6%9%7%45%346%22%
1480
March1st to 10thDay
17%15%6%9%7%35%45%5%26%
1797
11th to 20thDay
17%13%5%8%7%35%446%30%
1890
21st to endDay
20%12%37%5%33445%34%
2356
April1st to 10thDay
22%12%46%6%33345%32%
2160
11th to 20thDay
21%8%46%6%33346%36%
2134
21st to endDay
24%10%345%34447%32%
2276
May1st to 10thDay
21%8%37%5%3445%6%34%
2492
11th to 20thDay
18%6%36%5%3445%6%39%
2478
21st to endDay
17%8%35%5%345%6%7%36%
2725
June1st to 10thDay
24%7%36%5%35%45%7%30%
2520
11th to 20thDay
16%6%26%5%45%5%6%8%37%
2520
21st to endDay
21%6%45%5%46%5%5%8%32%
2520
July1st to 10thDay
12%6%35%5%25%46%8%42%
2520
11th to 20thDay
14%6%25%5%36%6%8%8%37%
2520
21st to endDay
14%5%35%5%35%6%7%10%38%
2744
August1st to 10thDay
14%6%36%5%45%6%6%8%37%
2506
11th to 20thDay
11%5%37%5%36%6%7%9%39%
2253
21st to endDay
14%6%35%5%35%5%7%8%40%
2376
September1st to 10thDay
14%6%245%345%6%8%42%
2160
11th to 20thDay
16%6%25%424347%47%
2100
21st to endDay
15%6%36%5%345%5%8%40%
1980
October1st to 10thDay
22%7%35%5%35%5%5%6%32%
1836
11th to 20thDay
20%10%47%7%45%5%5%6%28%
1787
21st to endDay
28%12%46%5%34345%26%
1782
November1st to 10thDay
19%10%47%5%35%45%7%30%
1671
11th to 20thDay
18%13%5%8%6%345%6%6%26%
1628
21st to endDay
19%18%5%9%7%35%5%5%5%20%
1520
December1st to 10thDay
23%16%7%12%8%3444415%
1520
11th to 20thDay
21%16%6%10%5%34445%20%
1906
21st to endDay
26%18%5%10%7%3444317%
2772
January1st to 10thNight
17%19%7%11%9%4445%316%
2649
11th to 20thNight
18%18%6%12%7%45%44418%
2660
21st to endNight
13%14%7%10%9%5%5%45%5%24%
2798
February1st to 10thNight
16%15%7%14%9%46%445%17%
2340
11th to 20thNight
15%13%6%11%8%45%5%45%24%
2188
21st to endNight
15%16%6%9%7%34445%27%
1776
March1st to 10thNight
19%15%5%8%8%45%33426%
2150
11th to 20thNight
17%14%5%7%6%34445%30%
2067
21st to endNight
21%12%37%5%2434435%
1998
April1st to 10thNight
24%11%47%6%3444429%
1800
11th to 20thNight
23%8%27%6%35%446%32%
1775
21st to endNight
21%10%47%44435%6%33%
1684
May1st to 10thNight
25%8%46%5%24446%32%
1481
11th to 20thNight
18%7%37%5%35%45%6%38%
1415
21st to endNight
16%5%35%6%35%46%8%39%
1550
June1st to 10thNight
22%7%37%5%25%5%6%9%30%
1440
11th to 20thNight
18%6%345%4445%8%39%
1440
21st to endNight
17%7%36%5%4446%7%36%
1440
July1st to 10thNight
11%5%35%435%5%7%9%43%
1440
11th to 20thNight
12%5%25%5%35%7%8%8%41%
1440
21st to endNight
13%6%25%4445%8%9%40%
1574
August1st to 10thNight
13%5%25%425%47%10%44%
1432
11th to 20thNight
14%5%36%5%35%46%7%42%
1628
21st to endNight
13%7%35%5%345%7%8%41%
1980
September1st to 10thNight
15%6%26%5%35%45%7%42%
1800
11th to 20thNight
17%5%25%42345%7%47%
1859
21st to endNight
19%5%245%3436%6%41%
1980
October1st to 10thNight
21%8%35%6%345%5%6%35%
2120
11th to 20thNight
20%10%37%5%45%5%5%5%31%
2173
21st to endNight
25%11%37%6%35%345%26%
2574
November1st to 10thNight
21%12%46%5%345%6%6%29%
2407
11th to 20thNight
20%12%47%6%3445%5%30%
2550
21st to endNight
22%14%6%9%6%34446%22%
2660
December1st to 10thNight
21%19%8%10%6%35%5%4415%
2660
11th to 20thNight
23%16%6%9%6%35%43421%
3288
21st to endNight
28%16%6%10%6%3343317%
4884

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
70%6%9%12%3
1518
11th to 20thDay
69%49%10%8%1
1520
21st to endDay
62%6%13%11%7%1
1592
February1st to 10thDay
66%5%10%13%41
1616
11th to 20thDay
61%5%12%14%7%1
1665
21st to endDay
64%5%10%12%8%1
1480
March1st to 10thDay
59%5%13%13%8%2
1800
11th to 20thDay
54%5%13%13%11%2
1890
21st to endDay
53%48%18%13%3
2356
April1st to 10thDay
56%48%19%11%2
2160
11th to 20thDay
51%49%21%15%2
2134
21st to endDay
53%5%10%15%12%4
2276
May1st to 10thDay
50%6%9%18%16%2
2492
11th to 20thDay
45%6%10%21%16%2
2482
21st to endDay
46%8%12%20%12%2
2725
June1st to 10thDay
52%6%12%17%12%1
2520
11th to 20thDay
44%7%12%23%13%2
2520
21st to endDay
50%8%12%18%10%1
2520
July1st to 10thDay
38%7%13%28%13%1
2450
11th to 20thDay
40%8%15%28%9%
2445
21st to endDay
40%9%18%24%9%
2591
August1st to 10thDay
43%9%16%24%8%
2492
11th to 20thDay
38%9%18%24%10%
2253
21st to endDay
40%8%15%25%12%1
2376
September1st to 10thDay
38%8%13%26%14%1
2160
11th to 20thDay
38%5%12%32%13%1
2100
21st to endDay
42%7%15%26%10%1
1980
October1st to 10thDay
51%6%13%20%10%
1836
11th to 20thDay
56%7%15%15%7%
1787
21st to endDay
61%5%12%15%6%1
1782
November1st to 10thDay
53%6%13%20%7%1
1671
11th to 20thDay
58%6%12%14%8%1
1628
21st to endDay
66%7%12%11%3
1520
December1st to 10thDay
72%7%10%9%2
1520
11th to 20thDay
65%8%11%12%3
1906
21st to endDay
70%7%8%11%3
2772
January1st to 10thNight
71%5%10%10%4
2649
11th to 20thNight
69%6%9%10%6%
2660
21st to endNight
60%6%11%13%9%1
2798
February1st to 10thNight
69%6%9%11%5%1
2340
11th to 20thNight
61%411%16%7%
2190
21st to endNight
60%49%15%11%
1776
March1st to 10thNight
62%5%9%14%9%1
2160
11th to 20thNight
56%5%10%17%9%3
2068
21st to endNight
54%48%19%12%3
1998
April1st to 10thNight
58%410%16%11%2
1800
11th to 20thNight
54%5%10%18%12%1
1775
21st to endNight
54%48%16%13%4
1684
May1st to 10thNight
54%46%15%17%4
1481
11th to 20thNight
46%5%8%19%18%3
1416
21st to endNight
42%7%15%19%15%2
1551
June1st to 10thNight
51%8%11%18%11%1
1440
11th to 20thNight
44%6%13%19%16%2
1440
21st to endNight
46%8%13%22%11%
1440
July1st to 10thNight
35%9%14%24%18%1
1400
11th to 20thNight
36%9%13%31%11%
1392
21st to endNight
37%9%17%25%11%1
1486
August1st to 10thNight
35%10%17%26%11%
1422
11th to 20thNight
41%7%14%25%12%1
1628
21st to endNight
38%8%16%25%11%1
1980
September1st to 10thNight
41%7%12%26%13%1
1800
11th to 20thNight
37%6%12%32%11%
1859
21st to endNight
42%7%12%25%13%1
1980
October1st to 10thNight
49%7%10%22%10%1
2120
11th to 20thNight
53%7%12%19%8%
2173
21st to endNight
60%7%12%13%7%1
2574
November1st to 10thNight
54%7%13%16%9%1
2407
11th to 20thNight
56%5%13%16%7%2
2550
21st to endNight
63%7%11%13%4
2660
December1st to 10thNight
71%6%10%11%2
2660
11th to 20thNight
68%5%9%13%5%
3288
21st to endNight
70%8%9%10%2
4884

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
27%17%31%19%6%
180
11th to 20thDay
27%28%29%12%31
180
21st to endDay
21%20%39%17%3
178
February1st to 10thDay
30%29%33%8%
238
11th to 20thDay
24%26%37%12%1
323
21st to endDay
30%21%31%17%2
346
March1st to 10thDay
27%22%28%17%5%
420
11th to 20thDay
21%25%32%16%5%1
420
21st to endDay
29%19%24%16%11%
462
April1st to 10thDay
26%21%30%16%6%
420
11th to 20thDay
26%21%25%18%9%1
412
21st to endDay
29%15%30%17%8%1
420
May1st to 10thDay
25%16%33%17%8%1
423
11th to 20thDay
18%16%33%20%11%1
447
21st to endDay
19%16%30%24%8%3
485
June1st to 10thDay
27%14%27%22%7%2
450
11th to 20thDay
16%13%33%28%8%2
450
21st to endDay
22%12%32%20%11%2
450
July1st to 10thDay
14%9%32%25%15%4
445
11th to 20thDay
14%11%30%31%11%4
444
21st to endDay
13%10%32%31%12%2
488
August1st to 10thDay
15%8%30%28%16%3
446
11th to 20thDay
14%8%28%31%14%6%
439
21st to endDay
16%12%29%22%15%7%
495
September1st to 10thDay
15%9%30%25%15%6%
450
11th to 20thDay
17%12%21%25%17%7%
450
21st to endDay
16%12%26%27%15%4
450
October1st to 10thDay
24%16%24%18%14%4
450
11th to 20thDay
25%21%26%16%11%2
444
21st to endDay
35%14%27%17%7%
396
November1st to 10thDay
28%20%26%17%9%
365
11th to 20thDay
31%24%23%15%7%1
288
21st to endDay
27%25%26%17%6%
180
December1st to 10thDay
31%18%28%17%6%
180
11th to 20thDay
28%29%28%11%31
180
21st to endDay
32%25%25%14%31
198
January1st to 10thNight
24%23%33%18%3
760
11th to 20thNight
27%22%31%16%4
760
21st to endNight
19%19%36%22%4
800
February1st to 10thNight
22%23%33%18%3
720
11th to 20thNight
22%21%36%19%2
703
21st to endNight
23%19%35%21%2
592
March1st to 10thNight
27%18%31%20%4
720
11th to 20thNight
25%22%31%19%4
720
21st to endNight
26%15%27%26%6%
792
April1st to 10thNight
28%17%31%20%4
720
11th to 20thNight
27%16%29%21%6%
711
21st to endNight
27%14%29%22%8%
604
May1st to 10thNight
27%11%28%24%9%
401
11th to 20thNight
21%10%32%28%9%
354
21st to endNight
18%10%33%28%11%1
389
June1st to 10thNight
23%9%32%28%7%1
360
11th to 20thNight
19%10%28%31%12%1
360
21st to endNight
19%8%31%27%14%1
360
July1st to 10thNight
10%8%33%34%13%1
350
11th to 20thNight
11%7%29%38%14%1
348
21st to endNight
14%5%33%37%10%1
394
August1st to 10thNight
13%5%25%39%18%1
358
11th to 20thNight
15%7%23%34%20%2
564
21st to endNight
15%6%29%31%17%2
792
September1st to 10thNight
16%8%28%33%14%1
720
11th to 20thNight
16%9%24%33%15%3
720
21st to endNight
19%10%26%25%18%2
720
October1st to 10thNight
25%12%28%21%13%1
720
11th to 20thNight
25%16%25%24%9%1
720
21st to endNight
29%17%30%19%5%
792
November1st to 10thNight
27%19%26%22%6%
740
11th to 20thNight
25%21%29%16%9%1
760
21st to endNight
28%21%24%19%7%
760
December1st to 10thNight
30%21%28%16%4
760
11th to 20thNight
29%22%28%16%41
760
21st to endNight
33%21%29%14%3
836
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