Evermore Farms
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Evermore Farms clear sky chart from 2005-11-06 to 2025-05-26.

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	12% 6% 2 6% 4 4 5% 4 6% 8% 43%	114397
	Night	12% 6% 2 6% 4 4 4 4 6% 8% 45%	114879
Transparency	Day	38% 6% 10% 20% 19% 7%	118191
	Night	36% 5% 10% 18% 21% 8%	119224
Seeing	Day	16% 10% 23% 24% 19% 8%	15748
	Night	15% 9% 23% 30% 20% 3	25844

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	16% 5% 2 4 3 3 4 3 4 5% 51%	4056
	11th to 20th	Day	11% 6% 2 4 2 2 3 2 5% 6% 54%	4060
	21st to end	Day	20% 6% 2 7% 4 3 3 2 4 6% 43%	4512
February	1st to 10th	Day	16% 7% 2 6% 5% 3 4 4 5% 7% 40%	2000
	11th to 20th	Day	21% 7% 2 5% 3 3 3 3 5% 4 44%	1948
	21st to end	Day	16% 8% 2 5% 4 4 4 3 5% 6% 42%	1650
March	1st to 10th	Day	20% 8% 3 6% 4 4 3 3 4 6% 38%	4791
	11th to 20th	Day	8% 4 2 5% 4 4 4 3 5% 7% 54%	4980
	21st to end	Day	15% 7% 3 7% 4 4 3 3 4 4 46%	5465
April	1st to 10th	Day	12% 5% 2 6% 4 3 4 3 5% 6% 50%	2200
	11th to 20th	Day	10% 5% 2 6% 3 4 4 3 6% 7% 49%	2321
	21st to end	Day	8% 4 2 5% 4 3 4 4 6% 8% 51%	2600
May	1st to 10th	Day	9% 6% 2 7% 4 4 5% 4 6% 8% 45%	4212
	11th to 20th	Day	16% 8% 2 7% 5% 4 5% 4 6% 6% 38%	4211
	21st to end	Day	7% 4 2 5% 4 5% 5% 4 7% 10% 47%	4541
June	1st to 10th	Day	9% 6% 3 7% 6% 6% 7% 5% 8% 10% 33%	2470
	11th to 20th	Day	5% 4 2 5% 5% 5% 6% 5% 7% 12% 44%	2470
	21st to end	Day	5% 5% 2 7% 6% 7% 6% 6% 9% 11% 37%	2470
July	1st to 10th	Day	10% 7% 3 8% 7% 6% 7% 5% 9% 11% 26%	4120
	11th to 20th	Day	5% 5% 2 7% 6% 6% 7% 6% 9% 12% 34%	4120
	21st to end	Day	8% 8% 3 9% 8% 8% 8% 7% 10% 12% 20%	4466
August	1st to 10th	Day	12% 6% 2 6% 5% 6% 6% 5% 9% 13% 29%	4104
	11th to 20th	Day	7% 4 2 6% 5% 5% 6% 4 7% 10% 45%	3929
	21st to end	Day	7% 5% 2 5% 5% 4 5% 4 6% 9% 49%	4066
September	1st to 10th	Day	9% 7% 2 7% 5% 6% 6% 4 6% 10% 39%	2090
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 6% 8% 40%	2090
	21st to end	Day	13% 6% 2 6% 4 3 5% 3 5% 7% 45%	2090
October	1st to 10th	Day	13% 5% 2 5% 3 3 3 3 5% 6% 52%	2090
	11th to 20th	Day	12% 5% 1 3 3 2 3 3 4 6% 58%	1929
	21st to end	Day	10% 4 2 5% 3 4 4 3 4 6% 56%	2090
November	1st to 10th	Day	13% 5% 2 5% 3 3 3 4 5% 4 53%	1887
	11th to 20th	Day	14% 5% 1 5% 3 3 3 2 4 7% 53%	1800
	21st to end	Day	13% 6% 2 4 4 4 3 3 6% 7% 48%	1800
December	1st to 10th	Day	13% 6% 2 5% 5% 4 3 3 4 6% 48%	2930
	11th to 20th	Day	16% 7% 2 5% 4 3 3 3 5% 6% 47%	3373
	21st to end	Day	21% 7% 2 5% 3 3 3 3 4 6% 43%	4466
January	1st to 10th	Night	13% 5% 2 5% 4 3 3 3 5% 6% 53%	5889
	11th to 20th	Night	12% 6% 2 5% 4 4 4 4 5% 6% 48%	5900
	21st to end	Night	16% 9% 2 6% 3 3 3 3 5% 6% 43%	6428
February	1st to 10th	Night	15% 6% 2 6% 3 4 4 3 5% 6% 46%	2400
	11th to 20th	Night	19% 8% 2 5% 4 4 4 3 4 6% 43%	2338
	21st to end	Night	14% 7% 2 6% 4 4 4 3 4 7% 45%	1980
March	1st to 10th	Night	19% 8% 3 6% 4 3 4 3 5% 7% 38%	5061
	11th to 20th	Night	9% 4 1 4 3 3 5% 3 6% 8% 54%	4980
	21st to end	Night	15% 6% 2 5% 3 4 4 4 5% 6% 47%	5467
April	1st to 10th	Night	11% 5% 2 5% 4 3 4 4 6% 7% 49%	2200
	11th to 20th	Night	12% 5% 2 4 3 3 3 3 5% 8% 52%	2040
	21st to end	Night	7% 4 2 4 5% 3 5% 4 6% 7% 53%	1800
May	1st to 10th	Night	6% 5% 2 6% 5% 5% 5% 5% 6% 10% 44%	2903
	11th to 20th	Night	15% 5% 2 6% 5% 5% 4 5% 6% 7% 41%	2902
	21st to end	Night	6% 4 2 4 3 4 4 5% 6% 10% 51%	3130
June	1st to 10th	Night	9% 7% 2 6% 5% 5% 7% 5% 8% 11% 35%	1710
	11th to 20th	Night	4 4 2 7% 5% 5% 5% 5% 8% 12% 44%	1710
	21st to end	Night	6% 4 1 6% 4 5% 7% 7% 10% 13% 37%	1710
July	1st to 10th	Night	12% 7% 3 9% 6% 6% 6% 5% 8% 10% 29%	2840
	11th to 20th	Night	6% 4 2 7% 6% 7% 8% 6% 10% 14% 30%	2840
	21st to end	Night	10% 8% 3 9% 7% 7% 7% 6% 9% 13% 22%	3087
August	1st to 10th	Night	11% 6% 2 8% 5% 7% 7% 6% 9% 13% 27%	2825
	11th to 20th	Night	7% 4 3 7% 6% 5% 6% 5% 7% 11% 41%	2896
	21st to end	Night	6% 5% 2 6% 4 5% 5% 4 7% 9% 48%	3558
September	1st to 10th	Night	10% 6% 2 6% 5% 6% 6% 4 7% 9% 39%	2090
	11th to 20th	Night	12% 6% 2 7% 5% 5% 5% 4 5% 7% 42%	2090
	21st to end	Night	12% 5% 2 6% 4 5% 5% 4 5% 7% 46%	2090
October	1st to 10th	Night	12% 5% 2 5% 3 3 4 3 5% 6% 51%	2090
	11th to 20th	Night	12% 4 1 4 3 3 3 2 4 5% 58%	2249
	21st to end	Night	10% 4 1 5% 3 4 4 3 4 5% 57%	2508
November	1st to 10th	Night	11% 6% 2 5% 3 3 3 3 5% 7% 53%	2406
	11th to 20th	Night	14% 5% 2 5% 4 3 3 3 3 5% 53%	2600
	21st to end	Night	13% 4 2 6% 4 4 4 3 5% 6% 50%	2600
December	1st to 10th	Night	13% 5% 2 5% 3 3 3 3 5% 5% 54%	4250
	11th to 20th	Night	17% 5% 2 5% 4 3 3 3 5% 7% 47%	4822
	21st to end	Night	20% 7% 2 6% 4 4 4 3 4 5% 41%	6490

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	35% 3 5% 19% 29% 8%	4057
	11th to 20th	Day	32% 3 4 18% 31% 12%	4060
	21st to end	Day	45% 2 4 18% 21% 9%	4512
February	1st to 10th	Day	43% 4 9% 19% 18% 7%	2000
	11th to 20th	Day	43% 4 5% 20% 22% 6%	1958
	21st to end	Day	42% 5% 7% 15% 22% 9%	1650
March	1st to 10th	Day	49% 3 6% 11% 24% 7%	4791
	11th to 20th	Day	30% 4 7% 16% 23% 21%	4980
	21st to end	Day	43% 3 6% 20% 20% 9%	5465
April	1st to 10th	Day	36% 4 10% 21% 21% 9%	2200
	11th to 20th	Day	34% 5% 9% 20% 23% 10%	2321
	21st to end	Day	30% 6% 12% 25% 24% 4	2600
May	1st to 10th	Day	35% 8% 12% 25% 17% 3	4250
	11th to 20th	Day	45% 7% 11% 22% 14% 1	4215
	21st to end	Day	30% 9% 15% 23% 22% 2	4554
June	1st to 10th	Day	41% 11% 16% 18% 12% 2	2470
	11th to 20th	Day	31% 10% 17% 26% 15% 1	2470
	21st to end	Day	36% 12% 18% 17% 13% 4	2470
July	1st to 10th	Day	46% 12% 19% 16% 4 2	4055
	11th to 20th	Day	39% 12% 21% 22% 5% 1	4051
	21st to end	Day	51% 15% 17% 13% 4	4324
August	1st to 10th	Day	44% 8% 18% 26% 3	4091
	11th to 20th	Day	33% 7% 16% 28% 14% 1	3968
	21st to end	Day	32% 7% 15% 28% 16% 3	4066
September	1st to 10th	Day	40% 8% 14% 17% 16% 4	2090
	11th to 20th	Day	41% 8% 11% 18% 20% 2	2090
	21st to end	Day	38% 7% 10% 20% 19% 6%	2090
October	1st to 10th	Day	31% 4 5% 14% 33% 13%	3480
	11th to 20th	Day	17% 3 4 17% 28% 31%	3182
	21st to end	Day	24% 3 4 21% 35% 14%	3428
November	1st to 10th	Day	34% 4 8% 14% 27% 13%	1887
	11th to 20th	Day	32% 3 6% 21% 25% 12%	1800
	21st to end	Day	35% 6% 7% 19% 26% 7%	1800
December	1st to 10th	Day	38% 4 5% 17% 26% 10%	2930
	11th to 20th	Day	40% 3 8% 21% 21% 7%	3370
	21st to end	Day	43% 3 8% 21% 23% 3	4466
January	1st to 10th	Night	33% 2 6% 20% 31% 8%	5889
	11th to 20th	Night	36% 3 5% 20% 27% 9%	5900
	21st to end	Night	44% 3 5% 14% 27% 7%	6428
February	1st to 10th	Night	39% 4 8% 18% 20% 10%	2400
	11th to 20th	Night	44% 4 6% 16% 21% 9%	2339
	21st to end	Night	40% 5% 7% 15% 20% 13%	1980
March	1st to 10th	Night	47% 4 8% 14% 18% 10%	5061
	11th to 20th	Night	29% 3 8% 13% 27% 20%	4980
	21st to end	Night	38% 3 7% 19% 20% 13%	5467
April	1st to 10th	Night	34% 5% 10% 20% 22% 10%	2200
	11th to 20th	Night	30% 4 7% 24% 23% 11%	2040
	21st to end	Night	29% 7% 11% 24% 23% 7%	1800
May	1st to 10th	Night	32% 9% 15% 23% 17% 4	2930
	11th to 20th	Night	40% 8% 12% 23% 15% 1	2903
	21st to end	Night	25% 8% 14% 26% 22% 4	3138
June	1st to 10th	Night	39% 12% 17% 18% 13% 1	1710
	11th to 20th	Night	30% 9% 18% 27% 13% 2	1710
	21st to end	Night	32% 13% 21% 18% 12% 4	1710
July	1st to 10th	Night	47% 11% 21% 14% 5% 2	2795
	11th to 20th	Night	40% 12% 25% 17% 5% 1	2786
	21st to end	Night	50% 15% 18% 12% 4 1	2988
August	1st to 10th	Night	46% 8% 21% 21% 3	2814
	11th to 20th	Night	36% 8% 20% 23% 12% 2	2923
	21st to end	Night	32% 7% 15% 27% 17% 2	3558
September	1st to 10th	Night	39% 10% 16% 16% 14% 5%	2090
	11th to 20th	Night	40% 7% 12% 18% 18% 5%	2090
	21st to end	Night	36% 7% 11% 17% 22% 7%	2090
October	1st to 10th	Night	34% 3 8% 12% 34% 10%	3480
	11th to 20th	Night	18% 2 4 14% 27% 33%	3735
	21st to end	Night	21% 3 5% 20% 32% 19%	4120
November	1st to 10th	Night	32% 4 8% 15% 26% 14%	2406
	11th to 20th	Night	35% 3 6% 16% 27% 14%	2600
	21st to end	Night	35% 5% 8% 17% 26% 10%	2600
December	1st to 10th	Night	33% 4 6% 18% 32% 8%	4250
	11th to 20th	Night	39% 3 12% 17% 22% 8%	4824
	21st to end	Night	46% 3 6% 22% 21% 3	6490

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	25% 23% 38% 13% 2	300
	11th to 20th	Day	23% 24% 33% 13% 6% 1	300
	21st to end	Day	25% 26% 34% 12% 4	330
February	1st to 10th	Day	24% 15% 42% 15% 4	300
	11th to 20th	Day	38% 17% 32% 11% 2	300
	21st to end	Day	28% 17% 40% 11% 3	249
March	1st to 10th	Day	23% 20% 27% 23% 7%	429
	11th to 20th	Day	21% 16% 35% 20% 8% 1	500
	21st to end	Day	21% 15% 36% 20% 7% 1	550
April	1st to 10th	Day	21% 14% 29% 25% 10% 1	500
	11th to 20th	Day	12% 16% 30% 26% 13% 3	492
	21st to end	Day	13% 10% 26% 29% 19% 3	500
May	1st to 10th	Day	13% 12% 28% 27% 13% 7%	503
	11th to 20th	Day	15% 7% 24% 27% 20% 8%	527
	21st to end	Day	12% 5% 19% 29% 24% 10%	549
June	1st to 10th	Day	11% 4 17% 32% 26% 11%	490
	11th to 20th	Day	6% 5% 16% 28% 25% 20%	490
	21st to end	Day	8% 2 16% 31% 27% 17%	490
July	1st to 10th	Day	7% 2 8% 28% 30% 24%	485
	11th to 20th	Day	7% 1 8% 22% 38% 24%	484
	21st to end	Day	6% 1 9% 30% 36% 18%	532
August	1st to 10th	Day	11% 4 15% 23% 30% 17%	486
	11th to 20th	Day	9% 2 9% 27% 34% 19%	479
	21st to end	Day	12% 3 10% 27% 32% 17%	539
September	1st to 10th	Day	11% 3 14% 29% 30% 14%	490
	11th to 20th	Day	16% 2 13% 29% 29% 11%	490
	21st to end	Day	16% 5% 15% 27% 27% 9%	490
October	1st to 10th	Day	17% 5% 22% 29% 19% 9%	490
	11th to 20th	Day	13% 9% 23% 28% 20% 7%	490
	21st to end	Day	14% 9% 25% 26% 21% 4	539
November	1st to 10th	Day	20% 7% 25% 28% 16% 3	425
	11th to 20th	Day	18% 15% 36% 23% 5% 2	300
	21st to end	Day	15% 17% 31% 26% 9% 2	300
December	1st to 10th	Day	25% 18% 35% 16% 6% 1	300
	11th to 20th	Day	25% 16% 34% 18% 6% 1	300
	21st to end	Day	29% 16% 32% 16% 5% 2	330
January	1st to 10th	Night	22% 19% 33% 21% 5%	800
	11th to 20th	Night	21% 16% 30% 26% 7%	800
	21st to end	Night	20% 18% 34% 25% 3	880
February	1st to 10th	Night	20% 13% 30% 31% 6%	800
	11th to 20th	Night	24% 15% 32% 26% 3	783
	21st to end	Night	19% 15% 35% 28% 3	660
March	1st to 10th	Night	18% 15% 30% 32% 5%	800
	11th to 20th	Night	18% 14% 32% 27% 9% 1	800
	21st to end	Night	17% 14% 32% 26% 10%	880
April	1st to 10th	Night	15% 15% 31% 27% 12%	800
	11th to 20th	Night	15% 12% 27% 31% 14% 1	678
	21st to end	Night	9% 6% 27% 39% 19% 1	600
May	1st to 10th	Night	8% 8% 26% 39% 17% 2	600
	11th to 20th	Night	13% 3 22% 37% 23% 3	591
	21st to end	Night	11% 2 16% 34% 30% 7%	634
June	1st to 10th	Night	11% 2 12% 41% 31% 3	570
	11th to 20th	Night	5% 2 14% 34% 34% 12%	570
	21st to end	Night	7% 2 9% 38% 37% 7%	570
July	1st to 10th	Night	9% 1 9% 28% 39% 14%	555
	11th to 20th	Night	7% 1 6% 27% 47% 12%	552
	21st to end	Night	6% 2 8% 29% 46% 8%	624
August	1st to 10th	Night	8% 1 8% 34% 39% 11%	567
	11th to 20th	Night	10% 2 9% 28% 45% 7%	564
	21st to end	Night	11% 2 11% 29% 38% 8%	670
September	1st to 10th	Night	11% 3 11% 29% 38% 8%	760
	11th to 20th	Night	14% 3 12% 30% 37% 4	760
	21st to end	Night	13% 3 17% 31% 32% 4	760
October	1st to 10th	Night	14% 3 19% 33% 26% 6%	760
	11th to 20th	Night	13% 6% 22% 33% 22% 3	760
	21st to end	Night	12% 7% 23% 33% 22% 2	836
November	1st to 10th	Night	13% 9% 23% 33% 21% 2	780
	11th to 20th	Night	17% 11% 27% 31% 14% 1	800
	21st to end	Night	15% 12% 27% 31% 14% 1	800
December	1st to 10th	Night	19% 14% 28% 29% 9% 1	800
	11th to 20th	Night	20% 12% 28% 29% 10% 1	800
	21st to end	Night	26% 13% 26% 28% 7%	880

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