Hampton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hampton clear sky chart from 2005-11-05 to 2017-09-19.

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
22%
14881
13%
46765
5%
14838
30%
14838
14%
33921

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%
745
13%
2658
2%
741
30%
741
9%
1897
January16th to endNight
15%
768
15%
2551
3%
768
29%
768
12%
1786
February1st to 15thNight
17%
704
11%
2286
3%
701
27%
701
12%
1638
February16th to endNight
17%
631
11%
1997
3%
631
27%
631
10%
1499
March1st to 15thNight
16%
720
15%
2019
4%
720
28%
720
14%
1500
March16th to endNight
18%
768
15%
2112
4%
768
27%
768
14%
1554
April1st to 15thNight
17%
588
13%
1782
5%
588
25%
588
13%
1351
April16th to endNight
19%
540
13%
1620
7%
540
25%
540
16%
1169
May1st to 15thNight
22%
540
10%
1575
4%
540
27%
540
12%
1216
May16th to endNight
18%
561
8%
1496
2%
560
25%
560
12%
1187
June1st to 15thNight
24%
366
7%
1266
3%
366
28%
366
11%
987
June16th to endNight
29%
360
7%
1260
4%
360
33%
360
12%
947
July1st to 15thNight
33%
340
8%
1190
7%
340
38%
340
15%
834
July16th to endNight
28%
488
8%
1445
7%
457
31%
457
12%
1091
August1st to 15thNight
35%
539
9%
1608
7%
535
37%
535
17%
1186
August16th to endNight
34%
573
16%
1729
8%
573
40%
573
23%
1139
September1st to 15thNight
27%
594
14%
1854
7%
594
35%
594
20%
1255
September16th to endNight
36%
673
22%
1858
12%
673
44%
673
27%
1198
October1st to 15thNight
28%
660
19%
1974
8%
660
38%
660
21%
1343
October16th to endNight
20%
704
14%
2156
4%
704
29%
704
14%
1548
November1st to 15thNight
23%
719
14%
2394
7%
719
32%
719
15%
1703
November16th to endNight
24%
750
14%
2520
6%
750
33%
750
12%
1799
December1st to 15thNight
12%
750
12%
2535
3%
750
23%
750
8%
1920
December16th to endNight
12%
800
11%
2880
3%
800
23%
800
7%
2174

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
21%9%35%5%23446%32%
48052
Night
20%9%36%5%34446%31%
46934
TransparencyDay
53%5%11%19%9%
47739
Night
53%6%10%18%9%
46765
SeeingDay
30%17%27%17%6%1
6986
Night
27%16%29%20%5%
14881

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
15%13%48%5%23335%33%
1277
16th to endDay
15%13%5%7%424435%33%
1671
February1st to 15thDay
14%12%36%6%345%47%30%
1575
16th to endDay
14%13%5%8%5%43346%28%
1473
March1st to 15thDay
19%14%46%6%2333331%
1930
16th to endDay
17%12%47%6%23246%33%
2112
April1st to 15thDay
23%12%45%5%24335%28%
2165
16th to endDay
24%10%24423345%33%
2340
May1st to 15thDay
27%8%45%423435%28%
2374
16th to endDay
24%9%26%6%3435%6%27%
2623
June1st to 15thDay
27%10%46%5%24336%24%
2700
16th to endDay
26%8%35%42445%7%26%
2700
July1st to 15thDay
19%6%245%3446%7%34%
2700
16th to endDay
20%8%35%5%2445%6%31%
2605
August1st to 15thDay
20%7%345%245%5%7%33%
2340
16th to endDay
15%5%26%5%2445%8%38%
2472
September1st to 15thDay
18%7%24333447%40%
2104
16th to endDay
20%413213336%48%
1848
October1st to 15thDay
21%8%24422336%39%
1656
16th to endDay
23%10%26%5%33336%31%
1715
November1st to 15thDay
25%9%35%422346%33%
1464
16th to endDay
20%11%47%5%34445%30%
1440
December1st to 15thDay
26%10%45%6%2335%6%24%
1424
16th to endDay
22%11%46%7%23445%25%
1344
January1st to 15thNight
16%9%47%5%25%446%32%
2658
16th to endNight
16%10%36%5%34347%33%
2551
February1st to 15thNight
17%9%37%436%45%6%30%
2285
16th to endNight
15%12%6%8%6%24446%27%
1997
March1st to 15thNight
18%10%46%5%3435%5%31%
2007
16th to endNight
17%10%47%6%24345%32%
2112
April1st to 15thNight
22%11%36%6%3434428%
1782
16th to endNight
22%9%26%5%24346%31%
1620
May1st to 15thNight
24%9%46%6%235%45%26%
1575
16th to endNight
23%9%35%5%35%447%25%
1494
June1st to 15thNight
28%8%47%7%34346%22%
1266
16th to endNight
24%9%35%5%34445%27%
1260
July1st to 15thNight
17%8%46%5%345%6%7%30%
1260
16th to endNight
20%9%36%6%35%45%6%26%
1547
August1st to 15thNight
21%6%35%435%5%5%5%32%
1620
16th to endNight
15%7%2442446%8%39%
1729
September1st to 15thNight
21%7%2442445%7%36%
1854
16th to endNight
17%424423445%46%
1858
October1st to 15thNight
20%7%35%42235%6%38%
1974
16th to endNight
23%9%35%5%33345%33%
2156
November1st to 15thNight
21%8%36%5%34447%32%
2394
16th to endNight
21%8%36%5%34345%33%
2520
December1st to 15thNight
25%9%37%6%3343428%
2535
16th to endNight
24%12%46%5%2435%426%
2880

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
54%6%11%17%8%1
1278
16th to endDay
52%48%19%13%
1671
February1st to 15thDay
53%5%12%19%7%1
1578
16th to endDay
56%5%11%17%7%1
1473
March1st to 15thDay
57%38%17%10%1
1941
16th to endDay
54%38%17%13%2
2112
April1st to 15thDay
58%47%15%12%2
2165
16th to endDay
52%410%17%13%2
2340
May1st to 15thDay
58%5%7%17%9%1
2374
16th to endDay
57%6%10%19%5%
2627
June1st to 15thDay
62%5%9%15%6%1
2700
16th to endDay
56%6%12%16%7%
2700
July1st to 15thDay
46%8%15%19%10%
2541
16th to endDay
51%7%14%20%6%
2445
August1st to 15thDay
48%8%14%20%7%
2327
16th to endDay
43%8%13%25%9%
2472
September1st to 15thDay
45%5%12%23%11%1
2104
16th to endDay
38%5%10%28%15%1
1848
October1st to 15thDay
47%410%26%11%
1656
16th to endDay
55%5%10%19%9%
1715
November1st to 15thDay
54%5%11%16%11%
1464
16th to endDay
56%5%12%16%9%
1440
December1st to 15thDay
60%5%10%18%5%
1424
16th to endDay
58%411%14%9%
1344
January1st to 15thNight
52%7%11%18%8%1
2658
16th to endNight
50%6%10%21%10%
2551
February1st to 15thNight
51%6%12%17%10%
2286
16th to endNight
57%5%10%14%9%1
1997
March1st to 15thNight
53%5%8%18%11%1
2019
16th to endNight
53%5%7%18%13%1
2112
April1st to 15thNight
58%48%14%11%3
1782
16th to endNight
53%410%17%12%1
1620
May1st to 15thNight
58%7%8%16%8%1
1575
16th to endNight
58%8%10%15%6%
1496
June1st to 15thNight
63%410%15%31
1266
16th to endNight
57%7%9%16%8%
1260
July1st to 15thNight
50%7%12%20%8%
1190
16th to endNight
56%8%11%16%6%
1445
August1st to 15thNight
51%8%13%18%8%
1608
16th to endNight
41%8%16%24%9%
1729
September1st to 15thNight
46%6%10%24%11%
1854
16th to endNight
39%412%27%14%
1858
October1st to 15thNight
47%411%24%11%1
1974
16th to endNight
53%410%21%10%
2156
November1st to 15thNight
52%5%12%18%9%
2394
16th to endNight
53%5%12%18%8%
2520
December1st to 15thNight
60%48%19%6%
2535
16th to endNight
59%6%9%16%8%
2880

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
36%20%36%6%
60
16th to endDay
22%21%36%15%5%
199
February1st to 15thDay
26%22%29%16%5%
236
16th to endDay
24%23%28%18%4
221
March1st to 15thDay
30%24%27%13%3
270
16th to endDay
32%20%24%14%42
288
April1st to 15thDay
36%23%22%10%5%
270
16th to endDay
34%18%29%10%5%1
270
May1st to 15thDay
37%16%24%13%5%
330
16th to endDay
34%16%26%16%4
519
June1st to 15thDay
34%17%25%17%4
495
16th to endDay
33%14%26%17%7%
495
July1st to 15thDay
28%10%27%22%9%1
475
16th to endDay
26%10%33%22%6%
403
August1st to 15thDay
27%9%34%20%7%1
313
16th to endDay
20%12%31%24%9%2
332
September1st to 15thDay
24%11%33%22%5%1
315
16th to endDay
21%15%29%20%8%4
266
October1st to 15thDay
30%11%22%21%9%4
226
16th to endDay
30%22%27%13%5%
240
November1st to 15thDay
28%20%22%18%7%2
235
16th to endDay
30%21%25%17%4
240
December1st to 15thDay
35%22%25%12%3
224
16th to endDay
39%32%20%7%
64
January1st to 15thNight
27%22%26%19%3
745
16th to endNight
26%21%32%15%4
768
February1st to 15thNight
25%19%33%18%2
704
16th to endNight
26%23%26%18%3
631
March1st to 15thNight
28%18%32%18%2
720
16th to endNight
25%19%30%17%6%
768
April1st to 15thNight
31%15%29%18%5%
588
16th to endNight
28%15%33%17%5%
540
May1st to 15thNight
29%15%29%19%5%1
540
16th to endNight
27%16%34%16%4
561
June1st to 15thNight
31%10%27%26%4
366
16th to endNight
27%10%26%28%7%
360
July1st to 15thNight
22%5%33%30%7%
340
16th to endNight
24%8%30%28%7%
488
August1st to 15thNight
25%6%28%29%10%
539
16th to endNight
19%10%30%29%9%
573
September1st to 15thNight
26%9%32%21%8%
594
16th to endNight
21%11%27%26%12%
673
October1st to 15thNight
25%12%29%22%8%1
660
16th to endNight
30%18%28%18%5%
704
November1st to 15thNight
26%16%29%18%7%1
719
16th to endNight
26%21%24%21%6%
750
December1st to 15thNight
34%20%26%15%2
750
16th to endNight
34%24%23%14%3
800
Page generated at 2017-09-20 05:49:53. Version ac04

Copyright 2017 A. Danko


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