Hampton Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hampton Beach clear sky chart from 2005-11-06 to 2024-10-25.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	17% 7% 2 6% 4 4 4 4 5% 7% 39%	101144
	Night	18% 8% 2 6% 4 4 4 3 5% 6% 39%	97664
Transparency	Day	44% 6% 12% 22% 14% 2	100902
	Night	45% 6% 12% 21% 14% 2	97526
Seeing	Day	19% 9% 28% 29% 12% 3	15006
	Night	20% 10% 30% 28% 10% 1	23832

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 7% 3 5% 4 3 4 3 5% 6% 44%	2517
	11th to 20th	Day	17% 7% 3 7% 3 3 4 3 5% 5% 42%	2520
	21st to end	Day	20% 10% 3 7% 3 4 4 3 4 5% 36%	2772
February	1st to 10th	Day	18% 8% 3 5% 4 4 4 4 6% 7% 36%	1743
	11th to 20th	Day	14% 7% 2 7% 5% 4 4 4 6% 6% 41%	1848
	21st to end	Day	16% 11% 3 6% 5% 4 5% 4 4 5% 38%	1570
March	1st to 10th	Day	26% 13% 3 6% 3 4 4 3 4 6% 29%	3116
	11th to 20th	Day	15% 8% 2 6% 4 4 4 4 5% 7% 41%	3374
	21st to end	Day	24% 9% 2 6% 3 4 4 3 5% 6% 34%	3971
April	1st to 10th	Day	19% 9% 3 6% 5% 4 4 2 5% 6% 38%	2280
	11th to 20th	Day	17% 7% 2 5% 4 5% 5% 5% 6% 7% 38%	2300
	21st to end	Day	20% 6% 2 7% 4 5% 3 3 4 6% 38%	2470
May	1st to 10th	Day	21% 11% 3 7% 5% 4 4 3 5% 6% 30%	4106
	11th to 20th	Day	22% 8% 3 7% 5% 4 4 3 4 7% 33%	4133
	21st to end	Day	16% 5% 2 5% 3 3 5% 4 5% 8% 43%	4837
June	1st to 10th	Day	19% 8% 3 6% 4 4 5% 4 6% 8% 34%	2660
	11th to 20th	Day	15% 6% 2 6% 4 4 5% 4 6% 9% 40%	2660
	21st to end	Day	17% 7% 3 7% 5% 5% 5% 4 6% 8% 34%	2660
July	1st to 10th	Day	14% 6% 3 7% 5% 4 5% 5% 7% 10% 36%	4440
	11th to 20th	Day	9% 6% 2 6% 4 4 4 5% 7% 10% 41%	4440
	21st to end	Day	17% 6% 2 6% 5% 5% 4 4 6% 7% 37%	4814
August	1st to 10th	Day	14% 6% 2 7% 5% 5% 5% 4 6% 7% 37%	4121
	11th to 20th	Day	15% 8% 2 7% 4 5% 5% 3 5% 7% 38%	4045
	21st to end	Day	8% 3 1 4 4 4 6% 5% 7% 10% 47%	4217
September	1st to 10th	Day	12% 5% 1 5% 4 4 4 4 6% 7% 48%	2256
	11th to 20th	Day	15% 5% 2 5% 3 3 3 3 3 6% 53%	2090
	21st to end	Day	16% 6% 2 5% 4 3 4 2 5% 7% 45%	2090
October	1st to 10th	Day	22% 6% 2 5% 3 5% 4 3 5% 5% 41%	2090
	11th to 20th	Day	15% 5% 2 5% 4 4 4 3 5% 7% 47%	1848
	21st to end	Day	22% 5% 2 6% 3 4 4 3 5% 6% 40%	1825
November	1st to 10th	Day	17% 6% 2 6% 3 3 3 3 4 5% 49%	1671
	11th to 20th	Day	19% 6% 2 4 3 2 3 3 4 7% 46%	1710
	21st to end	Day	19% 7% 2 5% 3 3 4 3 5% 6% 43%	1710
December	1st to 10th	Day	19% 7% 3 6% 5% 3 4 3 5% 6% 39%	1562
	11th to 20th	Day	23% 5% 2 5% 3 3 3 2 4 5% 43%	1906
	21st to end	Day	24% 10% 2 6% 4 4 4 3 4 5% 34%	2772
January	1st to 10th	Night	19% 7% 2 5% 4 3 3 3 4 6% 45%	4429
	11th to 20th	Night	15% 8% 3 8% 5% 4 4 3 5% 5% 40%	4440
	21st to end	Night	22% 11% 3 7% 4 5% 4 3 5% 5% 31%	4884
February	1st to 10th	Night	16% 9% 2 6% 5% 4 4 4 6% 6% 38%	2432
	11th to 20th	Night	14% 9% 3 6% 5% 4 4 3 5% 5% 42%	2218
	21st to end	Night	18% 9% 2 5% 3 4 4 4 5% 7% 41%	1884
March	1st to 10th	Night	29% 10% 2 5% 3 3 3 2 4 5% 33%	3724
	11th to 20th	Night	14% 8% 2 8% 6% 5% 5% 4 5% 6% 37%	3585
	21st to end	Night	26% 7% 2 6% 4 3 4 3 6% 5% 33%	3658
April	1st to 10th	Night	19% 9% 2 6% 5% 4 3 4 4 6% 37%	1900
	11th to 20th	Night	20% 7% 2 6% 4 4 3 3 5% 6% 40%	1828
	21st to end	Night	20% 7% 3 8% 3 4 5% 3 4 4 38%	1710
May	1st to 10th	Night	23% 12% 3 8% 4 4 4 3 5% 7% 26%	2834
	11th to 20th	Night	20% 9% 4 7% 5% 6% 5% 5% 6% 8% 26%	2789
	21st to end	Night	18% 7% 2 6% 4 4 4 4 5% 7% 40%	2738
June	1st to 10th	Night	20% 8% 3 6% 5% 5% 4 3 5% 6% 36%	1520
	11th to 20th	Night	19% 7% 1 6% 4 3 4 4 7% 9% 37%	1520
	21st to end	Night	18% 7% 3 7% 4 4 5% 3 6% 7% 36%	1520
July	1st to 10th	Night	12% 7% 3 7% 6% 6% 6% 4 7% 9% 33%	2520
	11th to 20th	Night	10% 5% 2 8% 5% 4 5% 5% 7% 9% 39%	2520
	21st to end	Night	16% 8% 2 7% 4 4 5% 4 6% 6% 38%	2739
August	1st to 10th	Night	20% 6% 3 8% 4 5% 5% 4 5% 7% 34%	2762
	11th to 20th	Night	14% 8% 3 8% 5% 5% 5% 4 7% 8% 34%	2782
	21st to end	Night	10% 4 1 4 4 3 5% 4 6% 8% 50%	3436
September	1st to 10th	Night	13% 6% 2 5% 4 3 4 3 5% 7% 48%	1924
	11th to 20th	Night	15% 5% 1 4 3 3 3 2 4 6% 52%	2090
	21st to end	Night	15% 6% 2 5% 5% 4 3 3 5% 7% 44%	2090
October	1st to 10th	Night	20% 6% 3 6% 5% 3 3 3 5% 6% 40%	2090
	11th to 20th	Night	16% 5% 2 6% 3 4 4 3 5% 6% 46%	2326
	21st to end	Night	23% 6% 2 6% 3 4 3 3 4 5% 39%	2637
November	1st to 10th	Night	15% 6% 2 5% 3 4 5% 3 5% 6% 47%	2407
	11th to 20th	Night	17% 7% 2 6% 4 4 4 2 4 6% 45%	2470
	21st to end	Night	16% 7% 2 5% 4 3 4 3 5% 6% 44%	2470
December	1st to 10th	Night	20% 9% 2 6% 4 4 4 3 5% 5% 38%	2616
	11th to 20th	Night	20% 6% 2 6% 4 3 3 3 5% 6% 41%	3288
	21st to end	Night	23% 9% 3 6% 4 3 4 3 4 5% 36%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	40% 5% 10% 33% 12% 1	2518
	11th to 20th	Day	44% 5% 12% 24% 13% 1	2520
	21st to end	Day	50% 5% 10% 23% 9% 1	2772
February	1st to 10th	Day	46% 6% 14% 20% 12% 3	1743
	11th to 20th	Day	43% 5% 12% 21% 15% 3	1857
	21st to end	Day	48% 6% 10% 20% 14% 3	1570
March	1st to 10th	Day	57% 3 10% 15% 12% 2	3119
	11th to 20th	Day	40% 6% 15% 21% 14% 4	3374
	21st to end	Day	51% 4 6% 16% 16% 8%	3971
April	1st to 10th	Day	48% 4 9% 18% 17% 4	2280
	11th to 20th	Day	43% 6% 12% 21% 15% 3	2300
	21st to end	Day	47% 5% 9% 18% 18% 3	2470
May	1st to 10th	Day	53% 8% 12% 17% 9% 1	4120
	11th to 20th	Day	50% 8% 15% 15% 10% 2	4137
	21st to end	Day	36% 8% 14% 23% 18% 1	4837
June	1st to 10th	Day	47% 7% 13% 21% 11% 1	2660
	11th to 20th	Day	41% 7% 14% 20% 16% 3	2660
	21st to end	Day	46% 8% 12% 22% 11% 1	2660
July	1st to 10th	Day	43% 6% 12% 21% 16% 1	4370
	11th to 20th	Day	37% 5% 17% 27% 13% 1	4365
	21st to end	Day	44% 6% 13% 22% 13% 2	4661
August	1st to 10th	Day	44% 7% 17% 23% 8% 1	4107
	11th to 20th	Day	44% 6% 14% 26% 9% 1	4084
	21st to end	Day	30% 6% 15% 29% 18% 2	4217
September	1st to 10th	Day	35% 6% 13% 25% 20% 1	2256
	11th to 20th	Day	34% 4 10% 28% 22% 3	2090
	21st to end	Day	39% 5% 9% 23% 21% 2	2090
October	1st to 10th	Day	45% 5% 9% 22% 15% 4	2090
	11th to 20th	Day	36% 6% 11% 30% 15% 2	1848
	21st to end	Day	45% 5% 11% 22% 14% 3	1825
November	1st to 10th	Day	39% 5% 13% 26% 16% 2	1671
	11th to 20th	Day	40% 5% 9% 22% 21% 3	1710
	21st to end	Day	43% 5% 16% 21% 15% 1	1710
December	1st to 10th	Day	46% 5% 14% 17% 16% 2	1562
	11th to 20th	Day	44% 4 12% 18% 16% 5%	1906
	21st to end	Day	53% 5% 11% 20% 10% 2	2772
January	1st to 10th	Night	40% 4 13% 28% 12% 3	4429
	11th to 20th	Night	45% 6% 11% 22% 13% 3	4440
	21st to end	Night	55% 6% 10% 18% 10% 2	4884
February	1st to 10th	Night	46% 6% 13% 19% 13% 3	2432
	11th to 20th	Night	44% 5% 11% 21% 16% 3	2220
	21st to end	Night	42% 5% 10% 25% 14% 5%	1884
March	1st to 10th	Night	54% 4 9% 17% 12% 3	3734
	11th to 20th	Night	45% 6% 12% 17% 17% 3	3586
	21st to end	Night	51% 5% 6% 13% 17% 7%	3658
April	1st to 10th	Night	48% 6% 10% 17% 16% 3	1900
	11th to 20th	Night	45% 4 9% 20% 19% 3	1828
	21st to end	Night	48% 5% 9% 17% 17% 3	1710
May	1st to 10th	Night	57% 7% 11% 16% 8% 2	2840
	11th to 20th	Night	53% 8% 15% 13% 9% 2	2790
	21st to end	Night	42% 7% 15% 19% 15% 2	2739
June	1st to 10th	Night	49% 5% 12% 21% 13% 1	1520
	11th to 20th	Night	43% 8% 13% 20% 14% 2	1520
	21st to end	Night	44% 8% 13% 21% 13% 1	1520
July	1st to 10th	Night	45% 7% 13% 21% 14% 1	2480
	11th to 20th	Night	39% 7% 16% 23% 15%	2472
	21st to end	Night	45% 6% 12% 22% 14% 1	2651
August	1st to 10th	Night	50% 7% 13% 19% 11% 1	2752
	11th to 20th	Night	46% 8% 14% 21% 10%	2809
	21st to end	Night	30% 6% 15% 27% 22% 1	3436
September	1st to 10th	Night	36% 6% 11% 27% 20% 1	1924
	11th to 20th	Night	34% 4 10% 25% 25% 2	2090
	21st to end	Night	39% 6% 9% 25% 19% 2	2090
October	1st to 10th	Night	45% 6% 11% 23% 13% 3	2090
	11th to 20th	Night	37% 7% 12% 28% 15% 1	2326
	21st to end	Night	47% 5% 12% 22% 13% 2	2637
November	1st to 10th	Night	39% 6% 11% 23% 18% 3	2407
	11th to 20th	Night	41% 4 10% 23% 19% 3	2470
	21st to end	Night	40% 5% 14% 25% 14% 2	2470
December	1st to 10th	Night	48% 6% 11% 22% 12% 1	2616
	11th to 20th	Night	43% 5% 14% 18% 18% 1	3288
	21st to end	Night	50% 5% 10% 23% 11% 1	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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	24% 17% 26% 27% 7%	180
	11th to 20th	Day	20% 21% 33% 19% 7%	180
	21st to end	Day	19% 15% 32% 28% 6%	198
February	1st to 10th	Day	24% 16% 36% 21% 2	365
	11th to 20th	Day	20% 19% 40% 18% 3	456
	21st to end	Day	20% 16% 33% 25% 5% 1	382
March	1st to 10th	Day	21% 14% 34% 25% 6%	460
	11th to 20th	Day	18% 18% 37% 23% 3 1	460
	21st to end	Day	24% 15% 34% 19% 6% 2	506
April	1st to 10th	Day	24% 13% 34% 20% 7% 2	460
	11th to 20th	Day	19% 12% 40% 21% 7% 1	452
	21st to end	Day	22% 7% 33% 29% 7% 1	460
May	1st to 10th	Day	25% 8% 33% 25% 7% 1	463
	11th to 20th	Day	17% 8% 30% 33% 10% 2	487
	21st to end	Day	19% 4 25% 35% 14% 3	529
June	1st to 10th	Day	19% 4 24% 34% 16% 3	490
	11th to 20th	Day	13% 5% 30% 36% 14% 2	490
	21st to end	Day	18% 3 28% 36% 13% 2	490
July	1st to 10th	Day	17% 3 15% 39% 22% 4	485
	11th to 20th	Day	13% 4 18% 39% 22% 4	484
	21st to end	Day	11% 3 17% 49% 18% 2	532
August	1st to 10th	Day	12% 3 20% 36% 26% 3	486
	11th to 20th	Day	14% 4 19% 35% 23% 6%	479
	21st to end	Day	13% 3 18% 41% 18% 7%	539
September	1st to 10th	Day	16% 4 24% 29% 20% 7%	490
	11th to 20th	Day	19% 5% 23% 27% 18% 8%	490
	21st to end	Day	17% 4 28% 30% 15% 6%	490
October	1st to 10th	Day	25% 7% 23% 24% 17% 4	490
	11th to 20th	Day	17% 11% 26% 31% 14% 2	417
	21st to end	Day	25% 8% 30% 25% 11% 1	411
November	1st to 10th	Day	15% 11% 32% 28% 12% 3	365
	11th to 20th	Day	23% 15% 31% 25% 6% 1	370
	21st to end	Day	23% 14% 28% 24% 10% 1	370
December	1st to 10th	Day	20% 9% 40% 23% 8%	222
	11th to 20th	Day	21% 17% 39% 21% 3	180
	21st to end	Day	23% 17% 32% 21% 6% 2	198
January	1st to 10th	Night	21% 18% 39% 19% 3	760
	11th to 20th	Night	24% 17% 39% 17% 3	760
	21st to end	Night	19% 19% 38% 20% 4	836
February	1st to 10th	Night	22% 16% 38% 23% 2	760
	11th to 20th	Night	19% 17% 45% 16% 3	743
	21st to end	Night	22% 15% 36% 23% 4	628
March	1st to 10th	Night	22% 16% 36% 22% 4	760
	11th to 20th	Night	19% 14% 38% 23% 6%	760
	21st to end	Night	24% 12% 34% 24% 6%	836
April	1st to 10th	Night	23% 12% 33% 27% 5%	760
	11th to 20th	Night	23% 7% 35% 25% 8% 1	704
	21st to end	Night	22% 8% 31% 31% 7% 1	570
May	1st to 10th	Night	26% 5% 30% 29% 8% 1	570
	11th to 20th	Night	22% 5% 28% 34% 10% 1	551
	21st to end	Night	21% 5% 21% 36% 14% 2	411
June	1st to 10th	Night	22% 5% 21% 36% 14% 3	380
	11th to 20th	Night	20% 5% 21% 40% 13% 1	380
	21st to end	Night	20% 3 19% 41% 15% 1	380
July	1st to 10th	Night	17% 3 16% 43% 18% 2	370
	11th to 20th	Night	13% 4 13% 48% 22% 1	368
	21st to end	Night	15% 3 14% 47% 20% 1	416
August	1st to 10th	Night	14% 2 13% 45% 24% 1	530
	11th to 20th	Night	14% 3 16% 42% 23% 2	562
	21st to end	Night	14% 3 17% 37% 25% 3	809
September	1st to 10th	Night	15% 3 24% 33% 23% 3	760
	11th to 20th	Night	16% 5% 21% 34% 19% 5%	760
	21st to end	Night	19% 4 24% 31% 19% 4	760
October	1st to 10th	Night	23% 6% 24% 28% 16% 3	760
	11th to 20th	Night	18% 9% 29% 30% 13% 2	760
	21st to end	Night	25% 8% 31% 26% 9%	812
November	1st to 10th	Night	16% 9% 35% 29% 10% 1	740
	11th to 20th	Night	20% 13% 36% 23% 7% 1	760
	21st to end	Night	20% 18% 34% 23% 5% 1	760
December	1st to 10th	Night	23% 13% 40% 19% 4 1	760
	11th to 20th	Night	22% 17% 35% 22% 3	760
	21st to end	Night	24% 16% 38% 20% 2	836

Page generated at 2024-10-22 20:21:03. Version ac07

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