Hammocks Beach State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hammocks Beach State Park clear sky chart from 2005-11-06 to 2026-04-17.

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	11% 6% 2 6% 4 4 5% 4 6% 8% 43%	130707
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 44%	131438
Transparency	Day	25% 39% 10% 13% 10% 4	134306
	Night	25% 38% 9% 13% 12% 4	135909
Seeing	Day	13% 8% 24% 28% 21% 6%	17423
	Night	14% 8% 24% 31% 19% 4	27543

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	10% 5% 2 5% 3 4 3 3 4 6% 56%	5258
	11th to 20th	Day	13% 4 2 4 3 3 4 2 5% 6% 54%	5280
	21st to end	Day	15% 11% 4 8% 4 4 4 2 4 6% 38%	5780
February	1st to 10th	Day	15% 6% 2 6% 5% 4 4 4 5% 7% 43%	1890
	11th to 20th	Day	19% 6% 3 5% 4 3 4 3 4 4 45%	2013
	21st to end	Day	14% 7% 2 7% 4 3 4 3 5% 7% 43%	1757
March	1st to 10th	Day	19% 8% 3 7% 4 4 4 3 5% 6% 37%	5045
	11th to 20th	Day	8% 4 2 5% 3 4 5% 4 5% 7% 54%	5090
	21st to end	Day	11% 5% 2 5% 3 3 4 4 5% 6% 52%	5626
April	1st to 10th	Day	10% 5% 2 5% 4 3 3 4 5% 6% 53%	2520
	11th to 20th	Day	8% 4 2 4 3 4 4 4 6% 7% 54%	2446
	21st to end	Day	8% 4 1 5% 4 3 3 3 6% 9% 54%	2400
May	1st to 10th	Day	6% 5% 2 7% 5% 5% 6% 5% 8% 10% 41%	5405
	11th to 20th	Day	14% 7% 3 7% 5% 5% 5% 5% 7% 10% 31%	5740
	21st to end	Day	9% 5% 2 6% 4 5% 5% 4 8% 10% 42%	6433
June	1st to 10th	Day	9% 6% 2 7% 5% 4 6% 5% 8% 10% 38%	2795
	11th to 20th	Day	8% 4 1 4 3 4 6% 5% 9% 12% 43%	2800
	21st to end	Day	7% 4 2 6% 5% 6% 6% 6% 9% 11% 38%	2667
July	1st to 10th	Day	7% 6% 3 7% 5% 5% 6% 5% 9% 13% 35%	5900
	11th to 20th	Day	5% 5% 2 7% 6% 6% 7% 5% 9% 14% 33%	5900
	21st to end	Day	7% 6% 3 8% 6% 6% 7% 5% 9% 13% 30%	6424
August	1st to 10th	Day	18% 12% 4 10% 5% 4 4 4 7% 10% 23%	4175
	11th to 20th	Day	7% 5% 2 6% 4 6% 7% 6% 7% 11% 39%	3850
	21st to end	Day	6% 6% 2 7% 5% 4 5% 4 7% 10% 43%	4312
September	1st to 10th	Day	9% 7% 3 6% 4 5% 5% 4 7% 10% 41%	2400
	11th to 20th	Day	14% 7% 3 7% 4 5% 5% 4 6% 8% 38%	2400
	21st to end	Day	17% 7% 3 7% 4 4 5% 3 5% 7% 39%	2107
October	1st to 10th	Day	13% 5% 3 7% 4 3 4 3 6% 7% 45%	2000
	11th to 20th	Day	9% 5% 2 5% 3 4 3 3 4 6% 56%	2000
	21st to end	Day	10% 5% 2 4 4 3 3 3 4 6% 55%	2200
November	1st to 10th	Day	12% 4 2 4 3 3 4 3 5% 6% 53%	2057
	11th to 20th	Day	11% 5% 3 6% 4 3 4 3 4 5% 52%	2000
	21st to end	Day	10% 5% 2 5% 5% 4 4 3 6% 8% 49%	1886
December	1st to 10th	Day	10% 6% 1 6% 4 3 4 3 5% 6% 52%	2680
	11th to 20th	Day	12% 7% 3 7% 5% 5% 4 3 4 5% 44%	3070
	21st to end	Day	11% 7% 3 6% 4 4 4 3 5% 7% 47%	4401
January	1st to 10th	Night	9% 5% 2 5% 4 3 3 3 5% 6% 54%	7635
	11th to 20th	Night	11% 5% 2 5% 3 3 3 4 6% 7% 51%	7680
	21st to end	Night	15% 8% 3 8% 4 4 3 3 4 5% 43%	8401
February	1st to 10th	Night	18% 6% 2 5% 4 4 4 3 5% 6% 44%	2730
	11th to 20th	Night	17% 8% 3 6% 4 4 3 3 5% 6% 41%	2491
	21st to end	Night	15% 7% 3 5% 4 4 4 4 5% 7% 41%	2045
March	1st to 10th	Night	17% 8% 3 7% 4 4 4 3 5% 5% 39%	5028
	11th to 20th	Night	13% 5% 2 5% 4 4 4 3 6% 7% 48%	5090
	21st to end	Night	12% 6% 2 5% 3 3 4 3 4 6% 52%	5547
April	1st to 10th	Night	10% 6% 3 5% 4 4 4 3 5% 7% 49%	2100
	11th to 20th	Night	8% 5% 2 6% 4 4 4 3 5% 6% 52%	2036
	21st to end	Night	8% 3 1 4 4 3 5% 5% 6% 8% 54%	2000
May	1st to 10th	Night	7% 6% 2 7% 5% 5% 6% 5% 8% 10% 40%	4490
	11th to 20th	Night	13% 7% 3 8% 5% 5% 5% 4 6% 8% 35%	4181
	21st to end	Night	11% 7% 3 7% 4 4 4 4 7% 9% 38%	4421
June	1st to 10th	Night	10% 8% 2 6% 6% 6% 5% 5% 7% 9% 37%	1600
	11th to 20th	Night	7% 6% 2 5% 4 5% 4 5% 8% 12% 43%	1600
	21st to end	Night	8% 6% 2 7% 4 5% 6% 5% 8% 12% 37%	1723
July	1st to 10th	Night	5% 4 3 8% 6% 6% 7% 5% 9% 13% 34%	4058
	11th to 20th	Night	6% 5% 2 8% 6% 6% 8% 7% 11% 17% 25%	4057
	21st to end	Night	7% 6% 3 7% 6% 7% 7% 6% 10% 13% 28%	4427
August	1st to 10th	Night	14% 11% 5% 9% 6% 5% 5% 5% 8% 11% 23%	2942
	11th to 20th	Night	7% 5% 2 8% 5% 6% 6% 6% 8% 12% 35%	3197
	21st to end	Night	7% 5% 2 6% 4 5% 5% 5% 7% 10% 42%	3586
September	1st to 10th	Night	11% 5% 2 5% 5% 5% 5% 6% 7% 10% 41%	2000
	11th to 20th	Night	12% 7% 2 7% 6% 5% 5% 4 6% 8% 36%	2000
	21st to end	Night	16% 8% 3 8% 4 4 4 4 6% 7% 37%	2286
October	1st to 10th	Night	11% 8% 3 6% 4 4 4 3 5% 6% 45%	2400
	11th to 20th	Night	10% 5% 3 6% 4 3 3 2 5% 6% 53%	2400
	21st to end	Night	9% 5% 2 5% 4 3 3 3 5% 6% 55%	2640
November	1st to 10th	Night	12% 5% 2 5% 4 3 4 4 4 6% 50%	2461
	11th to 20th	Night	12% 7% 3 6% 4 4 3 2 5% 6% 49%	2615
	21st to end	Night	11% 6% 2 5% 4 4 4 3 5% 8% 50%	2730
December	1st to 10th	Night	10% 6% 2 5% 3 3 3 3 4 6% 55%	4720
	11th to 20th	Night	13% 8% 2 7% 4 4 4 3 4 6% 44%	5345
	21st to end	Night	12% 5% 2 5% 4 3 4 3 5% 7% 49%	6776

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	24% 22% 9% 17% 22% 6%	5259
	11th to 20th	Day	25% 21% 4 13% 27% 11%	5280
	21st to end	Day	38% 25% 4 12% 13% 8%	5780
February	1st to 10th	Day	18% 59% 5% 9% 7% 2	1890
	11th to 20th	Day	20% 58% 4 8% 8% 2	2022
	21st to end	Day	17% 60% 4 8% 7% 4	1757
March	1st to 10th	Day	40% 29% 6% 8% 11% 5%	5045
	11th to 20th	Day	19% 29% 6% 12% 20% 14%	5090
	21st to end	Day	23% 29% 8% 19% 16% 6%	5626
April	1st to 10th	Day	15% 60% 5% 9% 8% 2	2520
	11th to 20th	Day	13% 61% 5% 13% 6% 3	2446
	21st to end	Day	10% 63% 7% 11% 8% 1	2400
May	1st to 10th	Day	27% 35% 17% 16% 4 1	5437
	11th to 20th	Day	35% 33% 12% 13% 6%	5744
	21st to end	Day	25% 33% 12% 18% 11% 1	6447
June	1st to 10th	Day	15% 65% 6% 7% 6% 1	2795
	11th to 20th	Day	9% 66% 10% 9% 5%	2800
	21st to end	Day	13% 64% 10% 10% 2	2667
July	1st to 10th	Day	30% 32% 26% 11% 1	5835
	11th to 20th	Day	30% 35% 28% 7%	5831
	21st to end	Day	34% 32% 16% 13% 4	6240
August	1st to 10th	Day	45% 39% 11% 4 1	4162
	11th to 20th	Day	23% 42% 11% 16% 7%	3886
	21st to end	Day	18% 39% 14% 23% 5%	4312
September	1st to 10th	Day	16% 61% 9% 7% 5% 1	2400
	11th to 20th	Day	23% 59% 5% 8% 4 2	2400
	21st to end	Day	22% 59% 8% 7% 3	2107
October	1st to 10th	Day	24% 37% 6% 16% 14% 4	3260
	11th to 20th	Day	11% 36% 4 12% 16% 22%	3240
	21st to end	Day	15% 36% 4 19% 18% 8%	3538
November	1st to 10th	Day	17% 55% 4 11% 11% 2	2057
	11th to 20th	Day	17% 55% 3 8% 12% 4	2000
	21st to end	Day	15% 54% 5% 11% 12% 3	1886
December	1st to 10th	Day	21% 35% 5% 11% 21% 7%	2680
	11th to 20th	Day	30% 31% 6% 12% 15% 5%	3066
	21st to end	Day	28% 28% 11% 20% 13% 1	4401
January	1st to 10th	Night	24% 22% 9% 18% 23% 5%	7636
	11th to 20th	Night	25% 21% 6% 12% 28% 9%	7680
	21st to end	Night	35% 24% 4 12% 17% 8%	8401
February	1st to 10th	Night	17% 60% 4 9% 8% 2	2730
	11th to 20th	Night	21% 58% 4 7% 7% 2	2493
	21st to end	Night	19% 59% 2 6% 10% 3	2045
March	1st to 10th	Night	39% 30% 5% 9% 13% 3	5028
	11th to 20th	Night	24% 29% 6% 9% 18% 14%	5090
	21st to end	Night	24% 28% 8% 18% 16% 4	5547
April	1st to 10th	Night	15% 60% 5% 9% 8% 2	2100
	11th to 20th	Night	15% 61% 6% 11% 5% 2	2036
	21st to end	Night	10% 64% 5% 14% 5% 1	2000
May	1st to 10th	Night	28% 34% 16% 17% 4 1	4520
	11th to 20th	Night	34% 32% 11% 16% 6%	4182
	21st to end	Night	30% 32% 12% 15% 10%	4429
June	1st to 10th	Night	16% 64% 8% 7% 5% 1	1600
	11th to 20th	Night	11% 65% 9% 11% 5%	1600
	21st to end	Night	13% 63% 9% 13% 3	1723
July	1st to 10th	Night	29% 33% 26% 12%	4015
	11th to 20th	Night	33% 35% 26% 5% 1	4006
	21st to end	Night	34% 35% 12% 14% 5%	4297
August	1st to 10th	Night	41% 41% 12% 5%	2931
	11th to 20th	Night	23% 43% 14% 14% 6%	3227
	21st to end	Night	19% 40% 12% 24% 5%	3586
September	1st to 10th	Night	16% 61% 9% 9% 4 1	2000
	11th to 20th	Night	21% 60% 6% 8% 4 2	2000
	21st to end	Night	22% 59% 9% 8% 3	2286
October	1st to 10th	Night	27% 37% 5% 12% 17% 3	3920
	11th to 20th	Night	10% 35% 3 10% 13% 28%	3899
	21st to end	Night	13% 36% 5% 21% 20% 6%	4252
November	1st to 10th	Night	19% 54% 5% 9% 11% 2	2461
	11th to 20th	Night	18% 54% 4 7% 12% 5%	2615
	21st to end	Night	14% 55% 4 12% 11% 3	2730
December	1st to 10th	Night	20% 35% 4 8% 24% 9%	4720
	11th to 20th	Night	30% 31% 11% 9% 13% 6%	5348
	21st to end	Night	26% 27% 10% 21% 14% 1	6776

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	17% 16% 41% 21% 5%	330
	11th to 20th	Day	12% 16% 38% 28% 5%	330
	21st to end	Day	19% 17% 34% 25% 4 1	363
February	1st to 10th	Day	21% 12% 34% 28% 6%	330
	11th to 20th	Day	26% 14% 37% 18% 5%	501
	21st to end	Day	16% 16% 38% 23% 7% 1	446
March	1st to 10th	Day	15% 15% 35% 23% 11% 1	540
	11th to 20th	Day	16% 17% 33% 26% 8% 1	540
	21st to end	Day	14% 12% 36% 25% 11% 2	594
April	1st to 10th	Day	14% 16% 32% 24% 12% 3	540
	11th to 20th	Day	10% 10% 29% 28% 19% 3	516
	21st to end	Day	9% 9% 30% 29% 20% 4	500
May	1st to 10th	Day	8% 13% 29% 31% 15% 4	503
	11th to 20th	Day	15% 5% 23% 34% 18% 5%	527
	21st to end	Day	11% 4 20% 29% 27% 10%	573
June	1st to 10th	Day	9% 3 20% 39% 23% 5%	530
	11th to 20th	Day	10% 3 14% 30% 32% 11%	530
	21st to end	Day	7% 3 14% 33% 32% 13%	530
July	1st to 10th	Day	10% 3 9% 27% 39% 12%	525
	11th to 20th	Day	8% 1 9% 28% 39% 15%	524
	21st to end	Day	9% 1 14% 29% 36% 10%	576
August	1st to 10th	Day	15% 3 13% 26% 32% 11%	526
	11th to 20th	Day	12% 2 8% 27% 34% 16%	519
	21st to end	Day	10% 3 11% 29% 32% 14%	583
September	1st to 10th	Day	10% 2 15% 29% 32% 12%	530
	11th to 20th	Day	18% 4 15% 29% 27% 7%	530
	21st to end	Day	18% 4 16% 28% 25% 9%	530
October	1st to 10th	Day	16% 5% 18% 27% 25% 8%	530
	11th to 20th	Day	12% 4 25% 34% 20% 6%	530
	21st to end	Day	11% 8% 22% 31% 21% 6%	583
November	1st to 10th	Day	15% 8% 25% 30% 18% 4	535
	11th to 20th	Day	12% 11% 36% 30% 11% 1	488
	21st to end	Day	10% 11% 31% 27% 19% 2	426
December	1st to 10th	Day	16% 9% 42% 26% 8%	220
	11th to 20th	Day	18% 11% 30% 27% 12% 1	220
	21st to end	Day	16% 13% 34% 26% 11% 1	325
January	1st to 10th	Night	15% 17% 34% 26% 6% 1	840
	11th to 20th	Night	15% 15% 29% 33% 8%	840
	21st to end	Night	16% 15% 36% 30% 3	924
February	1st to 10th	Night	21% 10% 35% 28% 6%	840
	11th to 20th	Night	22% 14% 35% 27% 3	823
	21st to end	Night	19% 13% 32% 28% 7%	692
March	1st to 10th	Night	16% 10% 36% 28% 9% 1	840
	11th to 20th	Night	16% 11% 33% 30% 9% 1	840
	21st to end	Night	14% 10% 34% 30% 11% 1	924
April	1st to 10th	Night	14% 11% 32% 30% 13% 1	840
	11th to 20th	Night	11% 9% 28% 33% 17% 2	816
	21st to end	Night	10% 6% 27% 39% 16% 2	800
May	1st to 10th	Night	10% 8% 29% 37% 15% 2	800
	11th to 20th	Night	15% 5% 23% 37% 19% 2	662
	21st to end	Night	10% 3 13% 32% 32% 9%	650
June	1st to 10th	Night	13% 3 14% 43% 24% 4	400
	11th to 20th	Night	9% 2 12% 36% 35% 7%	400
	21st to end	Night	11% 2 11% 35% 35% 6%	523
July	1st to 10th	Night	6% 2 9% 33% 41% 8%	585
	11th to 20th	Night	6% 1 8% 29% 46% 10%	582
	21st to end	Night	7% 9% 39% 35% 9%	657
August	1st to 10th	Night	11% 1 11% 28% 40% 8%	611
	11th to 20th	Night	11% 1 10% 32% 35% 11%	790
	21st to end	Night	13% 2 10% 27% 37% 11%	880
September	1st to 10th	Night	12% 1 11% 28% 37% 11%	800
	11th to 20th	Night	16% 2 14% 33% 29% 7%	800
	21st to end	Night	20% 3 14% 27% 29% 6%	800
October	1st to 10th	Night	15% 4 19% 28% 27% 7%	800
	11th to 20th	Night	13% 6% 24% 33% 21% 3	800
	21st to end	Night	12% 7% 24% 31% 21% 5%	880
November	1st to 10th	Night	15% 7% 24% 34% 17% 3	820
	11th to 20th	Night	15% 10% 31% 29% 14% 1	840
	21st to end	Night	13% 10% 30% 30% 16% 2	840
December	1st to 10th	Night	18% 13% 29% 30% 9% 1	840
	11th to 20th	Night	16% 12% 29% 30% 12% 1	840
	21st to end	Night	16% 12% 31% 31% 10%	924

Page generated at 2026-04-14 02:44:30. Version ac07

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