Hamlin Beach State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hamlin Beach State Park clear sky chart from 2005-11-06 to 2026-06-16.

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	15% 11% 4 9% 6% 5% 4 4 5% 7% 31%	138067
	Night	15% 12% 5% 11% 6% 5% 5% 4 5% 6% 27%	133935
Transparency	Day	51% 7% 12% 19% 10% 1	141651
	Night	55% 7% 12% 17% 9% 1	138438
Seeing	Day	21% 16% 29% 22% 10% 2	16530
	Night	22% 16% 29% 24% 9% 1	25884

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	15% 18% 9% 17% 9% 5% 4 3 3 4 13%	4661
	11th to 20th	Day	10% 25% 9% 19% 9% 6% 4 3 3 3 8%	4866
	21st to end	Day	14% 17% 7% 15% 12% 10% 6% 4 4 4 9%	5780
February	1st to 10th	Day	15% 17% 6% 15% 8% 6% 6% 4 5% 4 15%	1890
	11th to 20th	Day	13% 17% 9% 17% 9% 5% 5% 3 4 4 15%	1843
	21st to end	Day	18% 17% 5% 14% 9% 5% 4 4 4 5% 15%	1661
March	1st to 10th	Day	16% 13% 5% 12% 6% 5% 4 3 4 5% 28%	4940
	11th to 20th	Day	11% 14% 4 9% 6% 5% 5% 4 5% 7% 31%	5090
	21st to end	Day	16% 13% 5% 10% 5% 4 4 3 5% 6% 29%	5665
April	1st to 10th	Day	17% 13% 4 8% 5% 4 4 3 4 6% 31%	2520
	11th to 20th	Day	19% 10% 3 7% 5% 4 4 4 4 5% 36%	2494
	21st to end	Day	19% 10% 3 7% 5% 5% 4 3 4 7% 33%	2693
May	1st to 10th	Day	20% 9% 3 7% 5% 5% 4 3 5% 7% 32%	7838
	11th to 20th	Day	14% 9% 3 8% 5% 5% 4 4 5% 7% 36%	8221
	21st to end	Day	17% 6% 2 7% 4 4 4 4 6% 7% 39%	9060
June	1st to 10th	Day	14% 7% 2 6% 5% 5% 4 4 6% 8% 40%	2940
	11th to 20th	Day	11% 5% 2 6% 5% 4 5% 5% 6% 10% 39%	2870
	21st to end	Day	13% 6% 2 6% 5% 4 4 4 6% 8% 42%	2800
July	1st to 10th	Day	9% 5% 2 5% 4 5% 5% 4 6% 10% 45%	6360
	11th to 20th	Day	8% 6% 2 6% 5% 5% 5% 4 7% 9% 42%	6360
	21st to end	Day	9% 4 2 6% 4 4 5% 4 7% 9% 46%	6705
August	1st to 10th	Day	16% 6% 3 6% 4 5% 4 4 6% 7% 40%	4234
	11th to 20th	Day	13% 6% 3 7% 5% 5% 5% 4 6% 9% 36%	4174
	21st to end	Day	12% 6% 2 6% 4 4 5% 4 6% 8% 43%	4359
September	1st to 10th	Day	13% 6% 2 6% 4 4 5% 4 5% 8% 43%	2400
	11th to 20th	Day	13% 6% 2 6% 5% 4 3 3 5% 8% 45%	2388
	21st to end	Day	15% 7% 3 7% 5% 6% 6% 3 5% 8% 35%	2093
October	1st to 10th	Day	20% 7% 3 6% 5% 4 4 4 6% 5% 36%	2000
	11th to 20th	Day	18% 10% 4 10% 5% 5% 5% 3 6% 7% 28%	2000
	21st to end	Day	25% 13% 3 9% 6% 4 4 4 4 5% 23%	2200
November	1st to 10th	Day	13% 14% 4 9% 6% 4 4 4 5% 6% 29%	1808
	11th to 20th	Day	13% 17% 4 12% 5% 6% 4 4 5% 6% 23%	1680
	21st to end	Day	19% 18% 5% 10% 6% 5% 5% 3 5% 7% 17%	1680
December	1st to 10th	Day	18% 21% 7% 12% 7% 6% 5% 4 5% 5% 10%	2680
	11th to 20th	Day	20% 19% 7% 14% 5% 3 3 3 4 4 18%	3066
	21st to end	Day	21% 21% 7% 15% 8% 4 3 3 4 4 10%	4048
January	1st to 10th	Night	14% 19% 8% 22% 7% 5% 4 2 4 4 11%	8234
	11th to 20th	Night	10% 20% 9% 18% 9% 6% 5% 4 4 4 10%	8014
	21st to end	Night	14% 16% 5% 14% 11% 8% 7% 4 4 5% 12%	8401
February	1st to 10th	Night	15% 18% 5% 14% 8% 5% 5% 4 5% 5% 16%	2730
	11th to 20th	Night	13% 13% 7% 16% 9% 7% 5% 3 5% 4 18%	2663
	21st to end	Night	15% 16% 6% 15% 6% 6% 3 3 6% 6% 19%	2144
March	1st to 10th	Night	16% 11% 7% 13% 8% 5% 4 3 4 5% 25%	5114
	11th to 20th	Night	13% 12% 3 9% 6% 4 4 4 5% 8% 32%	5089
	21st to end	Night	17% 11% 4 12% 5% 4 4 3 5% 5% 31%	5508
April	1st to 10th	Night	19% 12% 3 9% 6% 4 5% 4 4 6% 28%	2100
	11th to 20th	Night	16% 10% 2 7% 5% 4 4 4 5% 7% 35%	2075
	21st to end	Night	18% 9% 3 7% 4 4 5% 5% 6% 7% 33%	1944
May	1st to 10th	Night	25% 9% 3 7% 4 5% 5% 4 5% 6% 27%	5047
	11th to 20th	Night	14% 8% 2 7% 5% 5% 5% 4 6% 8% 36%	4639
	21st to end	Night	17% 7% 2 7% 5% 4 4 3 6% 7% 38%	5114
June	1st to 10th	Night	13% 6% 2 7% 5% 5% 4 5% 7% 9% 37%	1680
	11th to 20th	Night	10% 5% 3 6% 5% 5% 5% 4 7% 9% 41%	1640
	21st to end	Night	12% 5% 3 7% 5% 5% 5% 4 5% 8% 41%	1600
July	1st to 10th	Night	11% 6% 3 7% 4 4 5% 4 7% 9% 41%	3600
	11th to 20th	Night	10% 6% 3 6% 4 4 4 4 6% 8% 44%	3600
	21st to end	Night	9% 5% 2 5% 4 4 4 3 6% 8% 49%	4143
August	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 5% 10% 43%	2915
	11th to 20th	Night	13% 6% 3 7% 4 5% 4 4 6% 8% 40%	2875
	21st to end	Night	9% 5% 2 6% 5% 4 6% 4 7% 9% 44%	3505
September	1st to 10th	Night	13% 5% 2 6% 4 3 4 4 6% 7% 46%	2000
	11th to 20th	Night	13% 5% 2 5% 4 4 4 3 5% 8% 48%	2010
	21st to end	Night	17% 7% 2 6% 5% 4 5% 4 7% 8% 36%	2305
October	1st to 10th	Night	18% 7% 2 7% 5% 5% 5% 4 6% 6% 35%	2400
	11th to 20th	Night	22% 8% 3 8% 4 4 4 4 5% 6% 30%	2400
	21st to end	Night	25% 12% 3 8% 4 4 4 5% 4 5% 25%	2640
November	1st to 10th	Night	16% 11% 3 7% 5% 4 5% 4 5% 6% 33%	2708
	11th to 20th	Night	14% 14% 5% 10% 7% 5% 5% 3 6% 7% 24%	2940
	21st to end	Night	19% 15% 6% 10% 6% 5% 5% 4 5% 6% 19%	2940
December	1st to 10th	Night	16% 19% 9% 15% 8% 6% 5% 4 5% 4 9%	4720
	11th to 20th	Night	17% 20% 6% 12% 6% 5% 4 3 5% 4 17%	5348
	21st to end	Night	24% 19% 7% 12% 7% 4 4 3 4 4 12%	7150

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	73% 7% 10% 8% 2	4662
	11th to 20th	Day	77% 6% 6% 5% 4 1	4897
	21st to end	Day	77% 6% 10% 6% 1	5780
February	1st to 10th	Day	70% 8% 10% 11% 1	1890
	11th to 20th	Day	72% 7% 8% 11% 2	1852
	21st to end	Day	70% 6% 9% 10% 4	1661
March	1st to 10th	Day	58% 6% 11% 16% 9%	4943
	11th to 20th	Day	51% 8% 18% 14% 9% 1	5090
	21st to end	Day	54% 7% 8% 20% 9% 1	5665
April	1st to 10th	Day	54% 6% 10% 17% 10% 2	2520
	11th to 20th	Day	50% 6% 9% 20% 13% 2	2494
	21st to end	Day	51% 7% 9% 18% 12% 2	2693
May	1st to 10th	Day	51% 7% 11% 18% 11% 2	7847
	11th to 20th	Day	46% 8% 12% 22% 11% 1	8225
	21st to end	Day	42% 7% 12% 24% 14% 1	9061
June	1st to 10th	Day	42% 7% 12% 21% 18% 1	2940
	11th to 20th	Day	39% 8% 14% 24% 15% 1	2870
	21st to end	Day	39% 8% 14% 23% 16% 1	2800
July	1st to 10th	Day	34% 7% 13% 28% 16% 1	6290
	11th to 20th	Day	36% 8% 15% 27% 13% 1	6285
	21st to end	Day	33% 8% 14% 30% 15%	6512
August	1st to 10th	Day	42% 8% 15% 22% 13% 1	4221
	11th to 20th	Day	43% 7% 16% 26% 8%	4213
	21st to end	Day	36% 7% 14% 33% 9% 1	4359
September	1st to 10th	Day	38% 8% 14% 28% 12% 1	2400
	11th to 20th	Day	37% 6% 13% 29% 14%	2388
	21st to end	Day	47% 7% 14% 22% 10% 1	2093
October	1st to 10th	Day	40% 8% 16% 24% 12%	3260
	11th to 20th	Day	47% 6% 16% 20% 13%	3240
	21st to end	Day	50% 7% 15% 22% 7% 1	3538
November	1st to 10th	Day	54% 7% 12% 17% 9% 1	1808
	11th to 20th	Day	59% 8% 14% 12% 6% 1	1680
	21st to end	Day	66% 7% 12% 12% 3	1680
December	1st to 10th	Day	73% 7% 12% 6% 1	2680
	11th to 20th	Day	70% 6% 10% 7% 7% 1	3066
	21st to end	Day	77% 6% 10% 6% 2	4048
January	1st to 10th	Night	75% 7% 9% 7% 2	8234
	11th to 20th	Night	74% 8% 8% 7% 4	8058
	21st to end	Night	72% 7% 9% 7% 5%	8401
February	1st to 10th	Night	67% 7% 11% 13% 2	2730
	11th to 20th	Night	67% 6% 11% 13% 3	2665
	21st to end	Night	63% 7% 12% 13% 5%	2144
March	1st to 10th	Night	60% 6% 12% 16% 6%	5124
	11th to 20th	Night	49% 7% 17% 18% 8% 2	5090
	21st to end	Night	52% 7% 9% 20% 10% 1	5508
April	1st to 10th	Night	56% 6% 9% 19% 9% 1	2100
	11th to 20th	Night	48% 7% 12% 18% 13% 2	2075
	21st to end	Night	46% 7% 11% 20% 13% 2	1944
May	1st to 10th	Night	56% 6% 9% 16% 11% 2	5054
	11th to 20th	Night	43% 9% 15% 18% 13% 1	4640
	21st to end	Night	44% 6% 12% 20% 16% 1	5115
June	1st to 10th	Night	41% 8% 12% 23% 14% 3	1680
	11th to 20th	Night	37% 7% 14% 22% 18% 2	1640
	21st to end	Night	40% 7% 13% 21% 17% 2	1600
July	1st to 10th	Night	37% 7% 14% 24% 17% 1	3560
	11th to 20th	Night	36% 7% 13% 26% 17% 2	3552
	21st to end	Night	31% 6% 13% 27% 21% 1	4021
August	1st to 10th	Night	36% 7% 15% 27% 13% 1	2904
	11th to 20th	Night	41% 7% 17% 25% 10%	2902
	21st to end	Night	32% 7% 14% 33% 12% 1	3505
September	1st to 10th	Night	36% 7% 14% 30% 13% 2	2000
	11th to 20th	Night	34% 6% 12% 30% 16% 1	2010
	21st to end	Night	43% 8% 13% 23% 12% 1	2305
October	1st to 10th	Night	43% 7% 11% 25% 13%	3920
	11th to 20th	Night	48% 6% 14% 19% 12% 1	3899
	21st to end	Night	46% 7% 13% 25% 8% 1	4252
November	1st to 10th	Night	49% 8% 13% 20% 9% 2	2708
	11th to 20th	Night	56% 8% 13% 15% 7% 1	2940
	21st to end	Night	62% 8% 15% 12% 2	2940
December	1st to 10th	Night	73% 8% 11% 6% 1	4720
	11th to 20th	Night	67% 8% 8% 9% 7% 1	5348
	21st to end	Night	75% 6% 9% 8% 2	7150

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	29% 28% 28% 10% 5%	220
	11th to 20th	Day	31% 27% 32% 8% 2	259
	21st to end	Day	28% 26% 29% 15% 3	363
February	1st to 10th	Day	27% 28% 33% 11% 2	330
	11th to 20th	Day	27% 32% 33% 7%	330
	21st to end	Day	35% 22% 32% 11%	377
March	1st to 10th	Day	22% 25% 33% 16% 4	540
	11th to 20th	Day	30% 22% 29% 16% 3 1	540
	21st to end	Day	30% 20% 31% 14% 5% 1	594
April	1st to 10th	Day	27% 21% 31% 16% 4	540
	11th to 20th	Day	29% 20% 28% 15% 7% 2	532
	21st to end	Day	24% 18% 34% 19% 5% 1	540
May	1st to 10th	Day	23% 14% 32% 22% 7% 2	543
	11th to 20th	Day	16% 12% 32% 26% 11% 2	567
	21st to end	Day	16% 10% 32% 26% 13% 3	617
June	1st to 10th	Day	16% 13% 31% 29% 10% 1	570
	11th to 20th	Day	14% 13% 28% 32% 11% 2	550
	21st to end	Day	13% 9% 35% 29% 12% 1	530
July	1st to 10th	Day	8% 7% 27% 34% 19% 4	525
	11th to 20th	Day	14% 6% 25% 33% 18% 4	524
	21st to end	Day	10% 6% 30% 38% 13% 3	576
August	1st to 10th	Day	10% 7% 21% 37% 19% 6%	526
	11th to 20th	Day	13% 5% 24% 33% 21% 5%	519
	21st to end	Day	11% 8% 27% 32% 17% 5%	583
September	1st to 10th	Day	15% 10% 22% 30% 18% 6%	530
	11th to 20th	Day	11% 7% 21% 27% 23% 11%	530
	21st to end	Day	15% 12% 29% 24% 15% 5%	530
October	1st to 10th	Day	21% 12% 26% 23% 13% 5%	530
	11th to 20th	Day	23% 20% 32% 15% 8% 2	530
	21st to end	Day	31% 16% 31% 17% 4	583
November	1st to 10th	Day	23% 21% 31% 17% 7% 2	380
	11th to 20th	Day	23% 27% 32% 14% 3 2	220
	21st to end	Day	31% 25% 30% 12% 3	220
December	1st to 10th	Day	30% 25% 27% 14% 3	220
	11th to 20th	Day	29% 31% 26% 11% 2	220
	21st to end	Day	34% 25% 27% 13% 1	242
January	1st to 10th	Night	25% 31% 29% 12% 3	840
	11th to 20th	Night	26% 27% 30% 15% 2	840
	21st to end	Night	22% 27% 32% 15% 4	924
February	1st to 10th	Night	26% 26% 32% 14% 1	840
	11th to 20th	Night	22% 27% 32% 16% 2	823
	21st to end	Night	25% 25% 32% 16% 2	692
March	1st to 10th	Night	25% 19% 34% 18% 3	840
	11th to 20th	Night	25% 21% 30% 19% 4	840
	21st to end	Night	23% 16% 34% 21% 7% 1	924
April	1st to 10th	Night	24% 16% 36% 20% 3	840
	11th to 20th	Night	23% 16% 30% 24% 6% 1	831
	21st to end	Night	24% 10% 30% 28% 8%	684
May	1st to 10th	Night	24% 8% 27% 27% 13% 1	561
	11th to 20th	Night	15% 7% 32% 36% 10%	414
	21st to end	Night	13% 6% 31% 31% 18% 1	455
June	1st to 10th	Night	13% 5% 31% 35% 15% 1	420
	11th to 20th	Night	12% 7% 28% 38% 16%	410
	21st to end	Night	12% 6% 27% 43% 12%	400
July	1st to 10th	Night	8% 4 23% 42% 21% 2	390
	11th to 20th	Night	11% 5% 24% 38% 21% 2	388
	21st to end	Night	11% 3 24% 42% 17% 3	528
August	1st to 10th	Night	10% 3 21% 41% 22% 3	597
	11th to 20th	Night	10% 5% 20% 36% 25% 3	594
	21st to end	Night	10% 4 24% 36% 24% 2	825
September	1st to 10th	Night	16% 6% 23% 30% 23% 3	800
	11th to 20th	Night	15% 5% 18% 30% 27% 6%	800
	21st to end	Night	17% 10% 21% 31% 17% 4	800
October	1st to 10th	Night	21% 10% 27% 24% 16% 2	800
	11th to 20th	Night	24% 15% 31% 22% 7% 1	800
	21st to end	Night	31% 13% 30% 22% 4	880
November	1st to 10th	Night	24% 15% 29% 24% 7%	820
	11th to 20th	Night	23% 24% 29% 17% 6% 1	840
	21st to end	Night	29% 21% 30% 15% 5%	840
December	1st to 10th	Night	31% 23% 29% 13% 3	840
	11th to 20th	Night	26% 27% 30% 14% 3	840
	21st to end	Night	33% 22% 30% 12% 2	924

Page generated at 2026-06-13 02:31:44. Version ac07

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