Merchants Millpond State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Merchants Millpond State Park clear sky chart from 2005-11-06 to 2024-11-05.

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	13% 6% 2 6% 5% 4 5% 4 6% 8% 41%	100926
	Night	14% 7% 2 6% 4 4 4 3 5% 7% 42%	98067
Transparency	Day	39% 6% 12% 21% 17% 4	104566
	Night	39% 6% 11% 21% 18% 5%	102566
Seeing	Day	18% 13% 27% 25% 14% 4	15315
	Night	17% 10% 29% 31% 13% 1	24967

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	17% 6% 2 5% 3 2 3 3 4 5% 51%	2772
	11th to 20th	Day	14% 8% 2 5% 3 3 3 3 5% 5% 49%	2840
	21st to end	Day	14% 10% 4 7% 4 4 4 3 4 5% 42%	3124
February	1st to 10th	Day	12% 8% 2 7% 4 4 5% 3 6% 7% 43%	1710
	11th to 20th	Day	19% 6% 2 5% 4 3 3 3 4 4 45%	1802
	21st to end	Day	17% 7% 3 6% 4 4 4 4 6% 6% 39%	1570
March	1st to 10th	Day	23% 10% 2 5% 4 3 4 3 5% 6% 36%	3369
	11th to 20th	Day	12% 5% 2 5% 3 3 3 2 4 6% 54%	3480
	21st to end	Day	17% 6% 2 6% 4 3 3 3 4 6% 45%	3900
April	1st to 10th	Day	13% 5% 2 4 3 3 3 3 5% 7% 52%	2280
	11th to 20th	Day	10% 6% 2 5% 5% 4 4 3 5% 7% 50%	2254
	21st to end	Day	11% 6% 2 7% 4 5% 5% 3 5% 6% 45%	2280
May	1st to 10th	Day	11% 7% 3 7% 6% 6% 5% 5% 7% 9% 34%	3765
	11th to 20th	Day	19% 7% 2 7% 5% 5% 5% 4 5% 7% 32%	4120
	21st to end	Day	8% 5% 3 6% 4 4 5% 4 6% 9% 45%	4823
June	1st to 10th	Day	10% 6% 3 6% 6% 5% 6% 5% 6% 10% 38%	2660
	11th to 20th	Day	9% 5% 2 5% 6% 6% 5% 5% 8% 10% 40%	2660
	21st to end	Day	8% 6% 3 6% 5% 6% 5% 6% 8% 12% 36%	2660
July	1st to 10th	Day	8% 4 2 6% 5% 5% 7% 6% 9% 13% 36%	4386
	11th to 20th	Day	11% 7% 3 8% 7% 5% 6% 5% 7% 9% 31%	4120
	21st to end	Day	10% 8% 3 9% 6% 6% 7% 5% 8% 9% 29%	4466
August	1st to 10th	Day	19% 8% 4 11% 6% 6% 6% 5% 6% 9% 21%	4082
	11th to 20th	Day	9% 7% 3 8% 5% 5% 6% 5% 8% 11% 33%	3730
	21st to end	Day	7% 5% 2 7% 5% 6% 6% 5% 7% 11% 40%	4180
September	1st to 10th	Day	13% 5% 2 7% 5% 5% 5% 5% 6% 9% 37%	2280
	11th to 20th	Day	13% 8% 2 7% 5% 5% 5% 3 6% 7% 38%	2280
	21st to end	Day	20% 8% 2 7% 5% 5% 5% 3 5% 6% 35%	2020
October	1st to 10th	Day	15% 8% 3 6% 3 4 3 4 4 8% 43%	1900
	11th to 20th	Day	13% 6% 1 5% 4 4 3 3 4 6% 51%	1900
	21st to end	Day	11% 5% 2 5% 4 3 4 3 4 5% 53%	2090
November	1st to 10th	Day	15% 5% 2 5% 3 3 4 3 4 6% 50%	1858
	11th to 20th	Day	16% 6% 2 5% 3 3 3 3 4 7% 51%	1710
	21st to end	Day	14% 5% 2 5% 4 4 3 3 4 7% 50%	1653
December	1st to 10th	Day	17% 6% 2 6% 4 4 3 4 5% 7% 41%	1520
	11th to 20th	Day	14% 7% 2 5% 2 2 2 3 3 5% 54%	1910
	21st to end	Day	16% 6% 3 6% 4 3 3 3 6% 7% 43%	2772
January	1st to 10th	Night	14% 8% 2 6% 3 4 4 3 5% 5% 46%	4169
	11th to 20th	Night	16% 8% 2 6% 4 3 3 3 5% 6% 43%	4120
	21st to end	Night	17% 7% 3 7% 4 4 3 3 4 5% 43%	4532
February	1st to 10th	Night	17% 7% 2 5% 4 4 4 3 5% 7% 43%	2470
	11th to 20th	Night	20% 9% 2 5% 4 3 3 3 5% 5% 41%	2262
	21st to end	Night	15% 8% 2 5% 4 3 3 3 5% 6% 46%	1884
March	1st to 10th	Night	25% 8% 2 6% 4 4 4 3 5% 5% 33%	3479
	11th to 20th	Night	13% 6% 2 6% 3 3 3 3 4 5% 51%	3480
	21st to end	Night	18% 7% 2 5% 3 3 3 2 4 5% 49%	3732
April	1st to 10th	Night	12% 6% 2 5% 4 4 4 3 6% 7% 46%	1900
	11th to 20th	Night	13% 6% 2 5% 4 3 4 3 4 7% 49%	1875
	21st to end	Night	13% 5% 3 5% 4 3 3 3 6% 7% 47%	1900
May	1st to 10th	Night	12% 8% 3 8% 6% 4 5% 4 6% 8% 36%	3130
	11th to 20th	Night	19% 7% 3 7% 4 4 4 4 5% 8% 35%	2796
	21st to end	Night	9% 6% 2 7% 4 4 5% 4 6% 11% 43%	2732
June	1st to 10th	Night	9% 5% 2 5% 4 5% 5% 5% 9% 12% 39%	1520
	11th to 20th	Night	8% 5% 3 6% 5% 4 5% 5% 7% 11% 40%	1520
	21st to end	Night	7% 6% 2 6% 4 5% 6% 5% 8% 9% 43%	1520
July	1st to 10th	Night	7% 6% 2 7% 5% 5% 6% 6% 9% 12% 35%	2569
	11th to 20th	Night	10% 8% 3 7% 5% 5% 6% 5% 7% 10% 34%	2840
	21st to end	Night	16% 9% 4 8% 5% 5% 5% 5% 7% 8% 29%	3087
August	1st to 10th	Night	19% 9% 3 8% 5% 5% 5% 4 5% 9% 28%	2825
	11th to 20th	Night	10% 7% 3 8% 6% 5% 5% 4 7% 9% 37%	3088
	21st to end	Night	8% 5% 2 5% 4 4 5% 5% 8% 10% 44%	3476
September	1st to 10th	Night	12% 5% 3 6% 4 3 5% 4 6% 9% 44%	1900
	11th to 20th	Night	13% 7% 2 7% 4 5% 4 3 5% 6% 43%	1900
	21st to end	Night	18% 8% 3 8% 5% 3 5% 3 5% 7% 35%	2154
October	1st to 10th	Night	14% 6% 2 5% 3 4 4 3 5% 5% 49%	2280
	11th to 20th	Night	12% 6% 2 5% 4 3 3 3 5% 5% 52%	2280
	21st to end	Night	11% 5% 2 5% 3 3 3 3 4 6% 53%	2508
November	1st to 10th	Night	16% 5% 3 4 3 3 4 3 4 5% 51%	2318
	11th to 20th	Night	15% 7% 2 4 4 3 3 3 5% 6% 49%	2470
	21st to end	Night	13% 4 2 5% 4 4 4 4 5% 6% 49%	2522
December	1st to 10th	Night	16% 8% 3 7% 5% 4 3 3 4 7% 39%	2660
	11th to 20th	Night	17% 6% 2 5% 4 3 4 3 4 7% 45%	3285
	21st to end	Night	15% 7% 2 5% 4 4 4 3 5% 7% 45%	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	36% 3 6% 27% 23% 4	2773
	11th to 20th	Day	37% 3 7% 18% 29% 6%	2840
	21st to end	Day	45% 5% 8% 19% 19% 5%	3124
February	1st to 10th	Day	41% 5% 11% 24% 16% 4	1710
	11th to 20th	Day	43% 4 6% 19% 20% 7%	1811
	21st to end	Day	44% 5% 12% 15% 18% 5%	1570
March	1st to 10th	Day	49% 4 9% 17% 14% 6%	3369
	11th to 20th	Day	32% 4 8% 20% 25% 11%	3480
	21st to end	Day	41% 5% 13% 18% 20% 4	3900
April	1st to 10th	Day	32% 5% 10% 23% 23% 7%	2280
	11th to 20th	Day	34% 5% 10% 24% 21% 7%	2254
	21st to end	Day	38% 6% 12% 23% 17% 5%	2280
May	1st to 10th	Day	43% 10% 16% 20% 9% 2	3800
	11th to 20th	Day	49% 8% 10% 22% 10% 1	4124
	21st to end	Day	34% 7% 14% 27% 16% 2	4837
June	1st to 10th	Day	39% 8% 13% 22% 16% 2	2660
	11th to 20th	Day	36% 8% 15% 24% 15% 1	2660
	21st to end	Day	38% 8% 16% 22% 14% 2	2660
July	1st to 10th	Day	35% 12% 20% 20% 10% 3	4317
	11th to 20th	Day	46% 9% 21% 17% 5% 1	4051
	21st to end	Day	47% 10% 13% 16% 11% 1	4324
August	1st to 10th	Day	57% 9% 16% 13% 5%	4069
	11th to 20th	Day	40% 10% 15% 23% 12% 1	3766
	21st to end	Day	35% 9% 13% 27% 14% 2	4180
September	1st to 10th	Day	41% 9% 14% 16% 17% 3	2280
	11th to 20th	Day	45% 5% 10% 22% 16% 2	2280
	21st to end	Day	50% 4 10% 19% 14% 3	2020
October	1st to 10th	Day	33% 5% 9% 23% 27% 4	3160
	11th to 20th	Day	25% 3 5% 20% 36% 11%	3140
	21st to end	Day	23% 3 6% 27% 30% 10%	3428
November	1st to 10th	Day	36% 4 9% 23% 23% 4	1858
	11th to 20th	Day	35% 3 10% 22% 23% 7%	1710
	21st to end	Day	36% 4 7% 26% 22% 5%	1653
December	1st to 10th	Day	42% 4 12% 20% 16% 4	1520
	11th to 20th	Day	34% 3 8% 29% 18% 8%	1906
	21st to end	Day	41% 4 9% 27% 18% 2	2772
January	1st to 10th	Night	38% 4 7% 24% 21% 5%	4169
	11th to 20th	Night	43% 4 6% 20% 21% 4	4120
	21st to end	Night	45% 5% 6% 19% 19% 7%	4532
February	1st to 10th	Night	41% 4 10% 23% 17% 5%	2470
	11th to 20th	Night	45% 4 7% 19% 19% 6%	2264
	21st to end	Night	41% 4 7% 22% 18% 7%	1884
March	1st to 10th	Night	53% 5% 9% 16% 14% 3	3479
	11th to 20th	Night	35% 5% 8% 17% 23% 12%	3480
	21st to end	Night	40% 4 8% 27% 17% 5%	3732
April	1st to 10th	Night	37% 6% 11% 17% 23% 6%	1900
	11th to 20th	Night	35% 5% 9% 25% 20% 6%	1875
	21st to end	Night	36% 5% 12% 25% 18% 4	1900
May	1st to 10th	Night	43% 10% 15% 21% 9% 1	3160
	11th to 20th	Night	46% 10% 10% 24% 9% 1	2797
	21st to end	Night	34% 9% 18% 25% 12% 1	2739
June	1st to 10th	Night	34% 10% 15% 26% 14% 1	1520
	11th to 20th	Night	36% 10% 17% 22% 14% 1	1520
	21st to end	Night	34% 11% 15% 24% 14% 3	1520
July	1st to 10th	Night	38% 14% 19% 19% 9% 2	2528
	11th to 20th	Night	43% 9% 24% 18% 5% 1	2786
	21st to end	Night	51% 9% 11% 17% 11%	2988
August	1st to 10th	Night	52% 8% 19% 17% 4	2814
	11th to 20th	Night	41% 9% 17% 22% 10%	3118
	21st to end	Night	33% 7% 14% 27% 17% 2	3476
September	1st to 10th	Night	34% 10% 18% 18% 16% 4	1900
	11th to 20th	Night	40% 7% 10% 20% 20% 2	1900
	21st to end	Night	47% 5% 12% 17% 16% 2	2154
October	1st to 10th	Night	38% 5% 9% 23% 23% 3	3800
	11th to 20th	Night	25% 3 6% 20% 31% 14%	3779
	21st to end	Night	21% 3 7% 29% 25% 14%	4120
November	1st to 10th	Night	36% 4 9% 21% 25% 5%	2318
	11th to 20th	Night	37% 4 9% 18% 23% 9%	2470
	21st to end	Night	36% 4 8% 24% 23% 6%	2522
December	1st to 10th	Night	46% 4 10% 19% 18% 4	2660
	11th to 20th	Night	39% 4 9% 21% 20% 6%	3288
	21st to end	Night	38% 5% 11% 24% 19% 2	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	22% 31% 32% 13% 2	252
	11th to 20th	Day	24% 27% 36% 11% 1	270
	21st to end	Day	26% 24% 40% 9% 1 1	297
February	1st to 10th	Day	21% 26% 37% 10% 4	270
	11th to 20th	Day	30% 27% 29% 11% 3	410
	21st to end	Day	26% 22% 32% 16% 4	382
March	1st to 10th	Day	22% 24% 35% 13% 5%	460
	11th to 20th	Day	25% 22% 33% 15% 5% 1	460
	21st to end	Day	22% 20% 37% 15% 5% 1	506
April	1st to 10th	Day	23% 18% 38% 14% 5% 1	460
	11th to 20th	Day	16% 19% 34% 19% 10% 3	452
	21st to end	Day	17% 17% 33% 24% 8% 1	460
May	1st to 10th	Day	16% 20% 32% 21% 9% 1	463
	11th to 20th	Day	20% 8% 33% 26% 10% 3	487
	21st to end	Day	18% 7% 23% 31% 16% 5%	529
June	1st to 10th	Day	13% 7% 28% 33% 18% 2	490
	11th to 20th	Day	13% 8% 21% 32% 21% 6%	490
	21st to end	Day	9% 6% 22% 35% 21% 6%	490
July	1st to 10th	Day	12% 3 15% 35% 26% 8%	485
	11th to 20th	Day	9% 2 14% 40% 29% 7%	484
	21st to end	Day	8% 4 23% 38% 20% 7%	532
August	1st to 10th	Day	15% 5% 18% 34% 21% 7%	486
	11th to 20th	Day	11% 3 18% 30% 28% 11%	479
	21st to end	Day	11% 3 16% 33% 26% 10%	539
September	1st to 10th	Day	14% 4 21% 26% 21% 14%	490
	11th to 20th	Day	17% 6% 20% 29% 20% 9%	490
	21st to end	Day	25% 8% 21% 23% 16% 6%	490
October	1st to 10th	Day	20% 7% 18% 27% 18% 8%	490
	11th to 20th	Day	15% 11% 30% 25% 16% 3	490
	21st to end	Day	16% 10% 30% 24% 14% 6%	539
November	1st to 10th	Day	19% 11% 29% 25% 12% 4	452
	11th to 20th	Day	19% 18% 29% 23% 11% 1	370
	21st to end	Day	19% 15% 26% 25% 13% 2	313
December	1st to 10th	Day	24% 18% 38% 16% 4 1	180
	11th to 20th	Day	19% 22% 32% 20% 6% 1	180
	21st to end	Day	27% 19% 24% 17% 11% 2	198
January	1st to 10th	Night	19% 19% 34% 23% 4 1	760
	11th to 20th	Night	21% 15% 34% 24% 6%	760
	21st to end	Night	18% 16% 40% 24% 2	836
February	1st to 10th	Night	22% 14% 39% 21% 4	760
	11th to 20th	Night	26% 19% 36% 17% 1	743
	21st to end	Night	20% 19% 37% 22% 3	628
March	1st to 10th	Night	19% 15% 36% 25% 5%	760
	11th to 20th	Night	21% 16% 38% 21% 5%	760
	21st to end	Night	20% 16% 36% 23% 5%	836
April	1st to 10th	Night	17% 18% 42% 21% 3	760
	11th to 20th	Night	15% 14% 39% 25% 7%	751
	21st to end	Night	16% 10% 38% 29% 7%	760
May	1st to 10th	Night	15% 13% 37% 29% 6%	760
	11th to 20th	Night	14% 8% 30% 37% 10% 1	558
	21st to end	Night	12% 2 23% 47% 16%	411
June	1st to 10th	Night	10% 4 24% 44% 17%	380
	11th to 20th	Night	9% 2 21% 46% 21% 2	380
	21st to end	Night	7% 3 21% 51% 16% 1	380
July	1st to 10th	Night	8% 2 16% 50% 22% 1	392
	11th to 20th	Night	10% 1 11% 44% 31% 4	552
	21st to end	Night	10% 3 17% 45% 24% 1	624
August	1st to 10th	Night	12% 2 13% 43% 25% 4	567
	11th to 20th	Night	13% 2 11% 45% 26% 4	741
	21st to end	Night	12% 3 13% 36% 32% 4	836
September	1st to 10th	Night	12% 2 16% 37% 27% 5%	760
	11th to 20th	Night	15% 6% 17% 33% 25% 4	760
	21st to end	Night	22% 5% 18% 32% 21% 1	760
October	1st to 10th	Night	16% 5% 19% 32% 23% 4	760
	11th to 20th	Night	16% 8% 29% 29% 15% 2	760
	21st to end	Night	15% 7% 28% 32% 16% 2	836
November	1st to 10th	Night	18% 7% 27% 31% 14% 3	760
	11th to 20th	Night	19% 10% 31% 30% 10% 1	760
	21st to end	Night	15% 11% 29% 31% 13% 1	760
December	1st to 10th	Night	21% 13% 31% 27% 7% 1	760
	11th to 20th	Night	17% 11% 34% 30% 7%	760
	21st to end	Night	19% 14% 31% 29% 7%	836

Page generated at 2024-11-03 02:11:29. Version ac07

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