Gipe Farm
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gipe Farm 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% 7% 3 7% 4 4 4 4 5% 7% 44%	131599
	Night	10% 7% 3 7% 4 4 4 3 5% 7% 47%	130840
Transparency	Day	39% 6% 12% 25% 16% 2	135211
	Night	37% 5% 12% 26% 18% 3	135280
Seeing	Day	14% 9% 31% 28% 14% 3	17678
	Night	14% 9% 33% 33% 10% 1	27700

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	9% 12% 4 13% 5% 4 4 3 5% 6% 33%	5289
	11th to 20th	Day	6% 9% 3 9% 7% 6% 6% 4 6% 7% 38%	5310
	21st to end	Day	7% 12% 5% 12% 6% 5% 4 4 4 6% 35%	5812
February	1st to 10th	Day	9% 12% 4 10% 6% 6% 4 4 5% 7% 32%	1890
	11th to 20th	Day	10% 10% 4 10% 5% 4 4 3 4 7% 39%	1844
	21st to end	Day	10% 8% 3 8% 5% 5% 4 3 5% 6% 44%	1728
March	1st to 10th	Day	16% 9% 3 5% 3 3 3 2 3 4 49%	5046
	11th to 20th	Day	11% 7% 2 6% 3 4 3 2 4 7% 50%	5090
	21st to end	Day	18% 11% 4 9% 5% 5% 5% 3 5% 7% 29%	5583
April	1st to 10th	Day	18% 8% 2 6% 4 4 4 2 4 6% 42%	2400
	11th to 20th	Day	17% 8% 2 6% 5% 4 5% 3 6% 6% 40%	2509
	21st to end	Day	20% 8% 2 6% 4 4 4 3 5% 7% 37%	2600
May	1st to 10th	Day	13% 7% 3 6% 4 4 5% 4 5% 7% 43%	5862
	11th to 20th	Day	14% 6% 2 5% 4 3 3 3 4 5% 50%	5862
	21st to end	Day	17% 8% 3 6% 4 4 4 3 6% 8% 38%	6748
June	1st to 10th	Day	8% 4 3 5% 5% 3 4 5% 7% 9% 47%	2800
	11th to 20th	Day	8% 5% 2 5% 4 4 5% 4 6% 9% 48%	2800
	21st to end	Day	7% 4 2 6% 6% 5% 6% 4 6% 8% 48%	2800
July	1st to 10th	Day	10% 4 2 5% 4 4 4 4 7% 9% 45%	6113
	11th to 20th	Day	6% 6% 2 6% 4 5% 5% 4 6% 9% 47%	5900
	21st to end	Day	6% 5% 2 5% 4 4 4 4 7% 9% 51%	6422
August	1st to 10th	Day	6% 4 2 5% 5% 4 6% 5% 7% 10% 46%	4234
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 6% 9% 42%	4171
	21st to end	Day	7% 4 2 7% 4 5% 5% 4 6% 8% 48%	4543
September	1st to 10th	Day	12% 4 2 4 3 3 4 3 5% 7% 54%	2370
	11th to 20th	Day	10% 5% 2 5% 3 4 4 2 5% 7% 53%	2200
	21st to end	Day	11% 5% 2 4 3 4 3 3 5% 6% 56%	2200
October	1st to 10th	Day	14% 5% 1 5% 2 2 3 2 5% 7% 52%	2019
	11th to 20th	Day	13% 7% 2 4 3 3 3 3 3 5% 55%	2000
	21st to end	Day	14% 7% 3 6% 5% 4 4 3 5% 6% 46%	2200
November	1st to 10th	Day	11% 5% 2 5% 4 3 3 4 5% 6% 53%	1923
	11th to 20th	Day	11% 8% 3 7% 4 3 3 3 5% 6% 48%	1774
	21st to end	Day	14% 8% 4 6% 4 3 4 3 5% 8% 41%	1680
December	1st to 10th	Day	5% 5% 2 8% 5% 4 4 3 5% 6% 51%	2690
	11th to 20th	Day	10% 9% 3 9% 5% 4 4 3 5% 6% 42%	3088
	21st to end	Day	18% 11% 5% 14% 4 4 4 4 4 5% 27%	4099
January	1st to 10th	Night	10% 9% 4 18% 7% 4 4 3 5% 6% 30%	7634
	11th to 20th	Night	5% 7% 3 8% 5% 5% 6% 4 7% 7% 42%	7680
	21st to end	Night	9% 12% 4 11% 5% 4 4 3 4 5% 39%	8402
February	1st to 10th	Night	11% 10% 4 8% 5% 5% 4 4 5% 6% 38%	2730
	11th to 20th	Night	10% 10% 3 7% 4 4 4 3 6% 7% 42%	2663
	21st to end	Night	9% 7% 3 7% 4 4 3 3 4 6% 49%	2095
March	1st to 10th	Night	14% 7% 2 4 3 3 3 3 4 5% 51%	5029
	11th to 20th	Night	10% 6% 2 5% 3 2 3 2 4 6% 56%	5090
	21st to end	Night	14% 9% 3 8% 4 4 4 4 6% 7% 36%	5588
April	1st to 10th	Night	13% 8% 3 5% 4 4 3 3 4 6% 46%	2218
	11th to 20th	Night	11% 7% 2 6% 4 4 4 4 5% 6% 46%	1969
	21st to end	Night	16% 9% 2 6% 3 4 3 3 4 6% 43%	1800
May	1st to 10th	Night	14% 6% 2 5% 3 3 3 3 4 5% 50%	4053
	11th to 20th	Night	14% 5% 2 4 2 3 3 3 5% 7% 54%	4053
	21st to end	Night	17% 6% 3 6% 3 4 3 3 5% 6% 43%	4124
June	1st to 10th	Night	5% 4 2 4 3 4 5% 5% 6% 10% 53%	1600
	11th to 20th	Night	7% 4 1 4 3 3 4 3 8% 11% 52%	1600
	21st to end	Night	5% 3 2 4 4 4 3 4 6% 8% 56%	1600
July	1st to 10th	Night	7% 5% 2 6% 4 4 4 4 5% 8% 52%	3846
	11th to 20th	Night	5% 4 2 5% 4 4 5% 4 6% 9% 55%	4077
	21st to end	Night	5% 4 2 4 4 4 4 4 6% 10% 52%	4449
August	1st to 10th	Night	4 3 1 4 3 4 3 4 6% 10% 59%	2926
	11th to 20th	Night	11% 5% 2 5% 3 3 3 3 5% 7% 52%	2888
	21st to end	Night	7% 4 1 4 3 3 4 4 6% 8% 56%	3362
September	1st to 10th	Night	9% 4 2 4 3 4 3 2 4 5% 58%	2026
	11th to 20th	Night	9% 5% 2 4 3 2 4 3 5% 7% 56%	2200
	21st to end	Night	9% 4 1 4 3 3 3 3 4 5% 60%	2200
October	1st to 10th	Night	13% 6% 2 5% 2 3 3 3 4 7% 54%	2360
	11th to 20th	Night	13% 6% 2 4 3 3 3 3 4 5% 54%	2400
	21st to end	Night	14% 7% 2 4 3 3 4 3 4 6% 50%	2640
November	1st to 10th	Night	9% 5% 2 5% 3 3 3 3 5% 7% 56%	2590
	11th to 20th	Night	10% 6% 2 5% 3 3 4 3 5% 6% 52%	2845
	21st to end	Night	13% 8% 3 6% 3 3 3 3 4 6% 48%	2940
December	1st to 10th	Night	6% 6% 2 6% 4 4 4 3 6% 7% 51%	4720
	11th to 20th	Night	10% 8% 3 7% 4 4 4 3 5% 7% 44%	5339
	21st to end	Night	18% 13% 6% 10% 4 3 3 3 4 5% 31%	7104

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	52% 5% 12% 20% 10%	5290
	11th to 20th	Day	45% 4 11% 21% 16% 3	5310
	21st to end	Day	51% 4 14% 21% 10%	5812
February	1st to 10th	Day	51% 6% 13% 19% 10% 1	1890
	11th to 20th	Day	45% 4 11% 23% 13% 3	1853
	21st to end	Day	42% 5% 12% 24% 14% 3	1728
March	1st to 10th	Day	40% 3 7% 25% 18% 5%	5046
	11th to 20th	Day	34% 4 8% 26% 23% 4	5090
	21st to end	Day	54% 6% 18% 16% 4 2	5585
April	1st to 10th	Day	44% 5% 11% 27% 12% 2	2400
	11th to 20th	Day	44% 5% 13% 23% 13% 2	2509
	21st to end	Day	48% 6% 11% 22% 13% 1	2600
May	1st to 10th	Day	38% 7% 11% 27% 15% 1	5900
	11th to 20th	Day	37% 5% 8% 26% 21% 3	5866
	21st to end	Day	44% 6% 11% 23% 15% 1	6762
June	1st to 10th	Day	32% 8% 16% 27% 14% 3	2800
	11th to 20th	Day	32% 7% 14% 29% 17% 1	2800
	21st to end	Day	33% 8% 14% 28% 14% 4	2800
July	1st to 10th	Day	33% 6% 14% 32% 14% 1	6049
	11th to 20th	Day	33% 7% 13% 28% 17% 2	5831
	21st to end	Day	27% 8% 18% 32% 14% 1	6240
August	1st to 10th	Day	30% 7% 15% 29% 18% 1	4220
	11th to 20th	Day	38% 6% 14% 25% 15% 1	4210
	21st to end	Day	33% 7% 14% 26% 15% 5%	4542
September	1st to 10th	Day	31% 6% 12% 28% 19% 4	2370
	11th to 20th	Day	32% 6% 11% 33% 18% 1	2200
	21st to end	Day	30% 4 10% 31% 25% 1	2200
October	1st to 10th	Day	20% 3 7% 21% 46% 3	3279
	11th to 20th	Day	21% 3 11% 30% 28% 7%	3240
	21st to end	Day	36% 4 8% 27% 22% 3	3538
November	1st to 10th	Day	32% 5% 13% 28% 20% 2	1923
	11th to 20th	Day	38% 4 14% 25% 18% 1	1774
	21st to end	Day	43% 5% 12% 27% 12% 1	1680
December	1st to 10th	Day	33% 5% 18% 30% 14%	2690
	11th to 20th	Day	44% 5% 16% 25% 10%	3085
	21st to end	Day	59% 5% 12% 18% 6%	4099
January	1st to 10th	Night	55% 5% 13% 16% 10% 1	7635
	11th to 20th	Night	38% 5% 12% 25% 18% 2	7680
	21st to end	Night	49% 4 14% 17% 15% 2	8402
February	1st to 10th	Night	47% 5% 13% 21% 12% 3	2730
	11th to 20th	Night	41% 5% 12% 24% 15% 3	2664
	21st to end	Night	37% 3 10% 23% 22% 4	2095
March	1st to 10th	Night	36% 3 7% 28% 23% 2	5029
	11th to 20th	Night	30% 4 7% 29% 23% 7%	5090
	21st to end	Night	45% 7% 18% 22% 6% 1	5588
April	1st to 10th	Night	39% 4 10% 27% 17% 3	2218
	11th to 20th	Night	38% 6% 11% 25% 17% 3	1969
	21st to end	Night	42% 5% 12% 23% 16% 2	1800
May	1st to 10th	Night	36% 5% 10% 25% 22% 2	4080
	11th to 20th	Night	32% 6% 10% 23% 25% 5%	4054
	21st to end	Night	42% 6% 13% 22% 16% 2	4132
June	1st to 10th	Night	25% 7% 16% 31% 17% 4	1600
	11th to 20th	Night	24% 7% 15% 28% 21% 4	1600
	21st to end	Night	24% 7% 14% 31% 20% 3	1600
July	1st to 10th	Night	30% 6% 13% 29% 18% 3	3804
	11th to 20th	Night	27% 7% 13% 29% 22% 2	4026
	21st to end	Night	25% 9% 17% 31% 17% 1	4320
August	1st to 10th	Night	22% 6% 15% 35% 20% 2	2916
	11th to 20th	Night	32% 6% 13% 28% 19% 2	2915
	21st to end	Night	26% 6% 16% 27% 17% 8%	3362
September	1st to 10th	Night	28% 5% 11% 27% 22% 6%	2026
	11th to 20th	Night	28% 5% 13% 33% 19% 3	2200
	21st to end	Night	27% 3 9% 29% 28% 4	2200
October	1st to 10th	Night	21% 3 6% 19% 49% 3	3854
	11th to 20th	Night	24% 3 7% 29% 29% 9%	3899
	21st to end	Night	36% 4 9% 28% 22% 2	4252
November	1st to 10th	Night	28% 5% 15% 25% 23% 4	2590
	11th to 20th	Night	33% 5% 11% 30% 18% 3	2845
	21st to end	Night	38% 4 12% 27% 17% 2	2940
December	1st to 10th	Night	33% 5% 12% 35% 14% 1	4720
	11th to 20th	Night	40% 5% 14% 29% 12%	5341
	21st to end	Night	56% 4 11% 21% 7% 1	7104

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% 14% 35% 25% 6% 1	330
	11th to 20th	Day	17% 16% 41% 19% 5% 1	330
	21st to end	Day	13% 11% 46% 25% 5%	363
February	1st to 10th	Day	18% 14% 46% 17% 4	330
	11th to 20th	Day	18% 18% 39% 19% 6% 1	330
	21st to end	Day	13% 17% 45% 19% 5%	273
March	1st to 10th	Day	20% 14% 44% 18% 4 1	330
	11th to 20th	Day	28% 12% 32% 20% 7% 1	330
	21st to end	Day	28% 18% 37% 13% 3 1	363
April	1st to 10th	Day	26% 18% 37% 15% 4	420
	11th to 20th	Day	21% 16% 35% 21% 6%	579
	21st to end	Day	22% 15% 34% 22% 7% 1	700
May	1st to 10th	Day	18% 13% 32% 24% 10% 2	703
	11th to 20th	Day	18% 10% 32% 26% 11% 3	725
	21st to end	Day	19% 7% 30% 28% 14% 2	789
June	1st to 10th	Day	7% 6% 24% 34% 23% 6%	730
	11th to 20th	Day	9% 5% 30% 33% 19% 4	730
	21st to end	Day	8% 6% 36% 32% 16% 3	730
July	1st to 10th	Day	9% 4 16% 35% 27% 10%	721
	11th to 20th	Day	6% 2 25% 38% 23% 6%	718
	21st to end	Day	6% 2 19% 43% 26% 5%	794
August	1st to 10th	Day	8% 3 21% 39% 25% 5%	726
	11th to 20th	Day	11% 4 18% 39% 25% 4	715
	21st to end	Day	10% 2 21% 37% 24% 6%	723
September	1st to 10th	Day	11% 5% 27% 31% 20% 5%	500
	11th to 20th	Day	6% 4 32% 32% 18% 6%	330
	21st to end	Day	14% 8% 29% 27% 19% 3	330
October	1st to 10th	Day	20% 6% 25% 29% 14% 5%	330
	11th to 20th	Day	11% 18% 44% 21% 6% 1	330
	21st to end	Day	18% 17% 36% 20% 7% 2	363
November	1st to 10th	Day	15% 12% 43% 21% 8% 2	330
	11th to 20th	Day	18% 15% 38% 20% 9%	330
	21st to end	Day	25% 12% 35% 20% 7% 1	330
December	1st to 10th	Day	9% 17% 38% 28% 7% 2	330
	11th to 20th	Day	17% 16% 35% 25% 7%	330
	21st to end	Day	21% 12% 45% 18% 3 1	363
January	1st to 10th	Night	12% 12% 36% 32% 6%	1050
	11th to 20th	Night	14% 14% 37% 28% 6%	1050
	21st to end	Night	16% 10% 39% 29% 5%	1155
February	1st to 10th	Night	16% 12% 38% 30% 4	1050
	11th to 20th	Night	14% 13% 40% 28% 5%	1029
	21st to end	Night	13% 12% 46% 23% 5% 1	711
March	1st to 10th	Night	14% 15% 39% 26% 6%	630
	11th to 20th	Night	19% 9% 38% 27% 6%	630
	21st to end	Night	22% 13% 40% 21% 5%	693
April	1st to 10th	Night	17% 16% 40% 23% 5%	630
	11th to 20th	Night	16% 16% 40% 25% 3	611
	21st to end	Night	19% 10% 37% 27% 7%	600
May	1st to 10th	Night	17% 8% 32% 34% 8% 1	600
	11th to 20th	Night	16% 8% 30% 35% 10% 1	591
	21st to end	Night	16% 6% 31% 33% 13%	650
June	1st to 10th	Night	6% 4 28% 43% 19%	600
	11th to 20th	Night	7% 3 31% 43% 16%	600
	21st to end	Night	6% 4 34% 42% 14%	600
July	1st to 10th	Night	7% 2 17% 43% 30% 2	585
	11th to 20th	Night	4 2 19% 49% 25% 2	582
	21st to end	Night	4 2 16% 51% 25% 1	657
August	1st to 10th	Night	6% 2 19% 49% 22% 2	597
	11th to 20th	Night	9% 3 15% 47% 24% 1	594
	21st to end	Night	7% 2 20% 43% 26% 2	660
September	1st to 10th	Night	9% 4 24% 37% 24% 2	600
	11th to 20th	Night	11% 3 29% 38% 18% 2	600
	21st to end	Night	11% 5% 30% 36% 17% 1	600
October	1st to 10th	Night	16% 6% 31% 33% 12% 2	760
	11th to 20th	Night	15% 10% 38% 30% 7%	800
	21st to end	Night	18% 12% 33% 29% 8%	880
November	1st to 10th	Night	11% 12% 33% 35% 9%	950
	11th to 20th	Night	13% 12% 40% 29% 5%	1050
	21st to end	Night	17% 11% 36% 28% 8%	1050
December	1st to 10th	Night	14% 12% 37% 31% 6%	1050
	11th to 20th	Night	17% 10% 36% 30% 6%	1050
	21st to end	Night	19% 13% 36% 28% 4	1155

Page generated at 2026-04-14 01:44:28. Version ac07

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