Montauk Point State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Montauk Point State Park clear sky chart from 2005-11-06 to 2024-11-02.

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 3 5% 7% 41%	101127
	Night	18% 8% 3 6% 4 4 4 3 5% 6% 38%	97863
Transparency	Day	42% 7% 13% 22% 14% 2	100885
	Night	46% 7% 13% 20% 13% 2	97725
Seeing	Day	18% 7% 24% 30% 17% 4	15153
	Night	20% 9% 27% 27% 14% 2	24109

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	16% 7% 2 5% 5% 5% 4 3 5% 6% 41%	2517
	11th to 20th	Day	18% 8% 2 5% 4 4 4 3 6% 6% 38%	2520
	21st to end	Day	23% 11% 3 7% 4 4 4 3 4 5% 33%	2772
February	1st to 10th	Day	18% 8% 3 6% 5% 4 5% 5% 5% 7% 35%	1860
	11th to 20th	Day	14% 8% 3 7% 4 4 4 3 5% 6% 42%	1848
	21st to end	Day	20% 9% 3 6% 3 3 4 2 6% 7% 38%	1570
March	1st to 10th	Day	26% 8% 2 4 3 3 3 2 4 6% 39%	3116
	11th to 20th	Day	11% 5% 1 4 3 4 4 3 6% 7% 52%	3306
	21st to end	Day	21% 8% 2 5% 4 4 4 4 5% 5% 38%	4086
April	1st to 10th	Day	18% 8% 2 5% 4 3 4 3 6% 6% 42%	2280
	11th to 20th	Day	18% 7% 2 5% 3 3 4 3 5% 7% 44%	2254
	21st to end	Day	18% 6% 2 6% 4 4 4 4 5% 6% 41%	2430
May	1st to 10th	Day	26% 12% 4 7% 4 3 3 2 4 6% 29%	4106
	11th to 20th	Day	22% 8% 3 6% 4 3 3 3 4 7% 36%	4101
	21st to end	Day	14% 9% 2 6% 3 3 4 3 5% 8% 42%	4837
June	1st to 10th	Day	17% 6% 1 6% 4 4 5% 4 6% 8% 39%	2660
	11th to 20th	Day	13% 7% 2 7% 3 4 5% 4 6% 9% 41%	2660
	21st to end	Day	12% 7% 2 5% 3 3 5% 4 7% 9% 43%	2660
July	1st to 10th	Day	14% 9% 3 7% 4 4 4 4 6% 8% 36%	4440
	11th to 20th	Day	12% 6% 2 5% 5% 4 5% 4 6% 10% 42%	4440
	21st to end	Day	18% 7% 2 6% 4 4 4 4 6% 8% 36%	4814
August	1st to 10th	Day	17% 7% 2 6% 5% 4 5% 3 6% 8% 37%	4117
	11th to 20th	Day	11% 5% 2 6% 5% 4 4 3 5% 8% 47%	3855
	21st to end	Day	7% 3 2 5% 4 4 5% 4 5% 8% 53%	4180
September	1st to 10th	Day	13% 6% 2 5% 4 4 3 3 5% 7% 47%	2280
	11th to 20th	Day	11% 6% 1 5% 3 3 3 3 4 7% 54%	2100
	21st to end	Day	19% 7% 2 5% 4 4 4 3 5% 7% 40%	2090
October	1st to 10th	Day	20% 6% 2 6% 3 3 3 3 5% 6% 44%	2090
	11th to 20th	Day	14% 7% 2 5% 3 2 3 3 5% 7% 49%	1886
	21st to end	Day	18% 6% 2 6% 4 4 3 4 5% 6% 42%	1881
November	1st to 10th	Day	17% 6% 2 5% 4 4 4 3 4 5% 47%	1681
	11th to 20th	Day	17% 6% 2 4 4 3 4 4 6% 7% 44%	1710
	21st to end	Day	17% 8% 3 5% 4 4 3 3 5% 6% 41%	1710
December	1st to 10th	Day	20% 9% 3 7% 4 4 4 4 5% 6% 35%	1592
	11th to 20th	Day	22% 7% 2 5% 3 3 3 3 4 7% 42%	1906
	21st to end	Day	20% 11% 4 9% 5% 3 3 2 4 6% 33%	2772
January	1st to 10th	Night	19% 7% 2 5% 3 3 3 2 5% 6% 44%	4429
	11th to 20th	Night	19% 10% 3 7% 3 3 4 3 4 4 38%	4440
	21st to end	Night	24% 12% 4 8% 5% 3 3 3 5% 5% 27%	4880
February	1st to 10th	Night	16% 10% 3 7% 5% 4 4 3 5% 6% 36%	2318
	11th to 20th	Night	19% 8% 2 6% 4 4 3 4 6% 7% 37%	2218
	21st to end	Night	19% 8% 3 6% 5% 4 4 4 5% 5% 38%	1884
March	1st to 10th	Night	27% 11% 2 5% 3 3 3 2 5% 5% 33%	3724
	11th to 20th	Night	11% 7% 2 7% 5% 4 4 4 6% 7% 44%	3653
	21st to end	Night	24% 9% 2 5% 4 4 4 3 5% 5% 36%	3544
April	1st to 10th	Night	19% 9% 3 6% 3 3 4 3 5% 7% 39%	1900
	11th to 20th	Night	17% 7% 2 7% 3 4 3 4 4 6% 42%	1875
	21st to end	Night	20% 9% 3 6% 4 3 4 3 5% 6% 39%	1748
May	1st to 10th	Night	23% 13% 5% 8% 4 4 3 3 4 6% 27%	2834
	11th to 20th	Night	25% 10% 3 7% 5% 4 4 3 7% 7% 25%	2813
	21st to end	Night	17% 9% 4 7% 4 3 5% 3 5% 7% 35%	2746
June	1st to 10th	Night	16% 9% 3 5% 5% 4 5% 4 5% 6% 37%	1520
	11th to 20th	Night	18% 6% 2 5% 4 3 3 3 6% 8% 41%	1520
	21st to end	Night	13% 8% 2 6% 5% 4 5% 3 6% 9% 39%	1520
July	1st to 10th	Night	17% 12% 3 6% 4 4 4 4 6% 7% 30%	2520
	11th to 20th	Night	12% 7% 3 6% 4 6% 5% 5% 8% 10% 35%	2520
	21st to end	Night	20% 9% 2 6% 5% 4 5% 3 5% 7% 33%	2739
August	1st to 10th	Night	20% 8% 3 8% 4 5% 5% 5% 7% 6% 30%	2780
	11th to 20th	Night	9% 5% 2 6% 4 5% 6% 5% 8% 8% 42%	2969
	21st to end	Night	8% 4 1 5% 3 4 4 3 5% 8% 55%	3476
September	1st to 10th	Night	14% 7% 2 6% 3 5% 5% 4 6% 6% 41%	1900
	11th to 20th	Night	13% 6% 2 6% 3 3 3 3 4 7% 51%	2079
	21st to end	Night	18% 7% 2 7% 5% 5% 4 3 4 5% 39%	2090
October	1st to 10th	Night	20% 7% 2 6% 4 3 4 3 4 6% 40%	2090
	11th to 20th	Night	15% 6% 2 6% 3 3 4 3 5% 6% 47%	2290
	21st to end	Night	20% 7% 3 6% 4 4 4 3 4 6% 39%	2717
November	1st to 10th	Night	15% 7% 2 6% 4 4 4 2 4 7% 44%	2431
	11th to 20th	Night	18% 9% 3 5% 3 4 4 3 5% 6% 41%	2470
	21st to end	Night	16% 7% 2 5% 4 4 4 4 5% 7% 42%	2470
December	1st to 10th	Night	21% 9% 3 6% 5% 4 5% 3 5% 6% 33%	2584
	11th to 20th	Night	20% 8% 2 7% 4 4 4 2 6% 6% 38%	3288
	21st to end	Night	20% 11% 3 7% 5% 3 3 3 4 5% 35%	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	43% 6% 12% 27% 12% 1	2518
	11th to 20th	Day	46% 7% 12% 23% 11% 2	2520
	21st to end	Day	53% 7% 9% 21% 9% 1	2772
February	1st to 10th	Day	47% 6% 15% 19% 12% 1	1860
	11th to 20th	Day	42% 6% 11% 24% 14% 2	1857
	21st to end	Day	47% 5% 13% 19% 14% 3	1570
March	1st to 10th	Day	47% 6% 13% 20% 12% 2	3119
	11th to 20th	Day	29% 6% 14% 35% 15% 1	3306
	21st to end	Day	47% 6% 8% 19% 16% 4	4086
April	1st to 10th	Day	41% 6% 12% 20% 18% 3	2280
	11th to 20th	Day	40% 5% 11% 23% 19% 3	2254
	21st to end	Day	42% 7% 10% 20% 18% 4	2430
May	1st to 10th	Day	56% 8% 13% 13% 9% 1	4120
	11th to 20th	Day	49% 7% 15% 17% 10% 2	4105
	21st to end	Day	37% 10% 12% 21% 18% 1	4837
June	1st to 10th	Day	42% 9% 12% 23% 14% 1	2660
	11th to 20th	Day	38% 8% 15% 24% 14% 1	2660
	21st to end	Day	36% 9% 14% 25% 15% 1	2660
July	1st to 10th	Day	44% 11% 12% 17% 14% 1	4370
	11th to 20th	Day	37% 9% 17% 24% 12% 1	4365
	21st to end	Day	45% 8% 14% 18% 14% 2	4661
August	1st to 10th	Day	45% 8% 17% 21% 9%	4103
	11th to 20th	Day	36% 8% 15% 31% 10% 1	3894
	21st to end	Day	28% 8% 16% 29% 19% 1	4180
September	1st to 10th	Day	36% 7% 13% 23% 20% 1	2280
	11th to 20th	Day	31% 6% 13% 24% 23% 3	2100
	21st to end	Day	44% 7% 9% 21% 18% 1	2090
October	1st to 10th	Day	41% 6% 11% 22% 16% 3	2090
	11th to 20th	Day	35% 5% 14% 26% 18% 1	1886
	21st to end	Day	41% 7% 14% 22% 14% 3	1881
November	1st to 10th	Day	41% 5% 15% 19% 18% 2	1681
	11th to 20th	Day	39% 6% 15% 21% 17% 2	1710
	21st to end	Day	43% 6% 14% 25% 10% 2	1710
December	1st to 10th	Day	50% 6% 13% 17% 13% 1	1592
	11th to 20th	Day	45% 4 15% 16% 17% 3	1906
	21st to end	Day	52% 6% 11% 21% 9%	2772
January	1st to 10th	Night	41% 5% 12% 30% 10% 3	4429
	11th to 20th	Night	48% 5% 14% 21% 10% 2	4440
	21st to end	Night	57% 6% 10% 16% 9% 1	4880
February	1st to 10th	Night	48% 6% 13% 20% 11% 2	2318
	11th to 20th	Night	46% 5% 11% 21% 14% 3	2220
	21st to end	Night	47% 5% 9% 22% 14% 3	1884
March	1st to 10th	Night	53% 6% 9% 20% 11% 2	3734
	11th to 20th	Night	37% 7% 15% 24% 14% 3	3654
	21st to end	Night	49% 5% 7% 13% 21% 5%	3544
April	1st to 10th	Night	45% 5% 11% 19% 17% 3	1900
	11th to 20th	Night	43% 6% 11% 18% 20% 2	1875
	21st to end	Night	46% 6% 10% 19% 16% 4	1748
May	1st to 10th	Night	58% 7% 13% 13% 8% 1	2840
	11th to 20th	Night	56% 9% 13% 13% 7% 2	2814
	21st to end	Night	44% 12% 12% 18% 13% 1	2747
June	1st to 10th	Night	46% 8% 12% 18% 15% 1	1520
	11th to 20th	Night	40% 7% 13% 24% 14% 1	1520
	21st to end	Night	41% 8% 13% 25% 14% 1	1520
July	1st to 10th	Night	51% 8% 11% 18% 12% 1	2480
	11th to 20th	Night	39% 10% 18% 23% 9% 1	2472
	21st to end	Night	49% 7% 15% 14% 13% 1	2651
August	1st to 10th	Night	50% 8% 17% 16% 8% 1	2770
	11th to 20th	Night	35% 10% 19% 27% 9%	2996
	21st to end	Night	26% 7% 17% 31% 19% 1	3476
September	1st to 10th	Night	41% 6% 10% 23% 17% 2	1900
	11th to 20th	Night	35% 5% 12% 23% 23% 2	2079
	21st to end	Night	47% 6% 8% 18% 18% 3	2090
October	1st to 10th	Night	46% 6% 10% 21% 14% 3	2090
	11th to 20th	Night	37% 6% 14% 26% 16% 1	2290
	21st to end	Night	46% 6% 13% 19% 14% 1	2717
November	1st to 10th	Night	41% 6% 12% 20% 17% 4	2431
	11th to 20th	Night	45% 5% 12% 20% 15% 3	2470
	21st to end	Night	40% 7% 14% 26% 11% 2	2470
December	1st to 10th	Night	51% 6% 13% 17% 11% 1	2584
	11th to 20th	Night	47% 6% 14% 17% 16% 1	3288
	21st to end	Night	51% 6% 12% 20% 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	19% 19% 32% 22% 8% 1	180
	11th to 20th	Day	19% 17% 40% 18% 5%	180
	21st to end	Day	20% 11% 39% 20% 8% 2	198
February	1st to 10th	Day	25% 9% 38% 21% 7%	420
	11th to 20th	Day	21% 14% 42% 21% 2	456
	21st to end	Day	23% 14% 32% 24% 6% 1	382
March	1st to 10th	Day	20% 10% 36% 27% 7%	460
	11th to 20th	Day	15% 14% 37% 28% 5% 1	460
	21st to end	Day	22% 9% 34% 25% 8% 2	506
April	1st to 10th	Day	23% 8% 32% 26% 10% 1	460
	11th to 20th	Day	20% 8% 29% 35% 8% 1	452
	21st to end	Day	23% 7% 23% 36% 10% 2	460
May	1st to 10th	Day	24% 9% 27% 29% 10% 1	463
	11th to 20th	Day	18% 3 29% 34% 14% 1	487
	21st to end	Day	20% 3 14% 31% 27% 5%	529
June	1st to 10th	Day	17% 2 18% 36% 24% 2	490
	11th to 20th	Day	13% 2 19% 37% 26% 4	490
	21st to end	Day	14% 2 16% 38% 25% 4	490
July	1st to 10th	Day	15% 4 8% 35% 31% 7%	485
	11th to 20th	Day	10% 3 9% 37% 33% 9%	484
	21st to end	Day	14% 2 11% 39% 30% 3	532
August	1st to 10th	Day	12% 2 12% 36% 31% 7%	486
	11th to 20th	Day	15% 2 9% 34% 32% 8%	479
	21st to end	Day	11% 1 13% 35% 28% 11%	539
September	1st to 10th	Day	17% 2 17% 30% 24% 10%	490
	11th to 20th	Day	15% 3 17% 29% 24% 11%	490
	21st to end	Day	25% 3 19% 33% 17% 3	490
October	1st to 10th	Day	24% 7% 18% 27% 18% 6%	490
	11th to 20th	Day	15% 8% 25% 31% 18% 3	457
	21st to end	Day	24% 7% 26% 28% 12% 3	429
November	1st to 10th	Day	17% 8% 25% 32% 14% 4	369
	11th to 20th	Day	22% 13% 30% 26% 9%	370
	21st to end	Day	18% 15% 32% 24% 10% 1	370
December	1st to 10th	Day	19% 14% 34% 25% 7%	252
	11th to 20th	Day	23% 16% 36% 19% 6%	180
	21st to end	Day	24% 12% 35% 20% 8% 2	198
January	1st to 10th	Night	21% 18% 35% 21% 4	760
	11th to 20th	Night	28% 16% 33% 19% 4	760
	21st to end	Night	22% 15% 39% 20% 3 1	836
February	1st to 10th	Night	20% 15% 39% 23% 2	760
	11th to 20th	Night	23% 15% 43% 16% 3	743
	21st to end	Night	23% 16% 35% 20% 5%	628
March	1st to 10th	Night	23% 13% 34% 23% 6%	760
	11th to 20th	Night	20% 9% 36% 28% 6% 1	760
	21st to end	Night	23% 9% 34% 25% 8% 1	836
April	1st to 10th	Night	23% 7% 31% 31% 7% 1	760
	11th to 20th	Night	20% 7% 28% 33% 11% 1	751
	21st to end	Night	23% 4 28% 30% 14% 1	608
May	1st to 10th	Night	23% 7% 21% 33% 13% 3	570
	11th to 20th	Night	21% 5% 28% 34% 12% 1	562
	21st to end	Night	23% 2 14% 30% 27% 4	419
June	1st to 10th	Night	17% 3 18% 36% 23% 2	380
	11th to 20th	Night	20% 3 15% 32% 28% 1	380
	21st to end	Night	16% 3 12% 40% 28% 1	380
July	1st to 10th	Night	15% 4 10% 38% 29% 4	370
	11th to 20th	Night	13% 2 9% 39% 32% 5%	368
	21st to end	Night	14% 2 13% 39% 30% 3	416
August	1st to 10th	Night	10% 1 13% 39% 32% 5%	535
	11th to 20th	Night	12% 3 10% 35% 32% 7%	671
	21st to end	Night	13% 2 11% 33% 31% 9%	836
September	1st to 10th	Night	17% 1 16% 32% 27% 7%	760
	11th to 20th	Night	16% 3 17% 30% 25% 9%	760
	21st to end	Night	21% 4 21% 31% 19% 4	760
October	1st to 10th	Night	25% 6% 21% 25% 19% 4	760
	11th to 20th	Night	18% 9% 27% 29% 14% 2	760
	21st to end	Night	22% 10% 32% 25% 10% 2	836
November	1st to 10th	Night	18% 10% 29% 28% 13% 3	748
	11th to 20th	Night	24% 14% 31% 23% 8% 1	760
	21st to end	Night	19% 16% 31% 24% 8% 1	760
December	1st to 10th	Night	25% 17% 31% 21% 6% 1	760
	11th to 20th	Night	23% 19% 33% 19% 5%	760
	21st to end	Night	24% 15% 38% 20% 4	836

Page generated at 2024-10-30 13:19:20. Version ac07

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