Mantese's Farm
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mantese's Farm clear sky chart from 2005-11-06 to 2026-02-16.

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	11% 7% 3 7% 4 4 4 4 6% 8% 42%	130873
	Night	13% 8% 3 7% 4 4 4 3 5% 7% 43%	130210
Transparency	Day	38% 6% 12% 25% 17% 3	134453
	Night	39% 6% 11% 24% 18% 3	134708
Seeing	Day	14% 8% 24% 26% 20% 8%	17292
	Night	15% 7% 28% 33% 15% 2	27236

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	12% 10% 5% 11% 6% 4 4 4 5% 6% 33%	4691
	11th to 20th	Day	7% 8% 3 8% 5% 6% 5% 4 5% 8% 42%	5052
	21st to end	Day	16% 13% 4 8% 4 4 4 3 4 5% 35%	5812
February	1st to 10th	Day	15% 10% 4 8% 4 4 4 4 4 7% 35%	1896
	11th to 20th	Day	17% 9% 3 8% 5% 4 4 3 4 6% 37%	1998
	21st to end	Day	13% 9% 2 8% 5% 4 5% 3 5% 7% 40%	1650
March	1st to 10th	Day	15% 10% 3 6% 4 2 2 2 3 4 48%	4498
	11th to 20th	Day	10% 7% 2 4 3 3 4 3 5% 7% 51%	4980
	21st to end	Day	12% 8% 3 8% 5% 4 5% 4 6% 8% 37%	5783
April	1st to 10th	Day	12% 6% 2 7% 5% 4 4 4 6% 7% 42%	2400
	11th to 20th	Day	16% 8% 3 6% 5% 4 4 3 5% 6% 42%	2374
	21st to end	Day	16% 7% 3 7% 5% 5% 5% 3 5% 7% 37%	2400
May	1st to 10th	Day	15% 8% 3 8% 5% 4 5% 4 7% 10% 30%	5579
	11th to 20th	Day	15% 8% 3 7% 4 4 5% 4 6% 8% 36%	6175
	21st to end	Day	13% 6% 2 7% 5% 5% 5% 4 5% 8% 40%	6935
June	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 7% 9% 46%	2800
	11th to 20th	Day	7% 4 2 4 4 4 4 4 7% 10% 49%	2800
	21st to end	Day	4 4 2 6% 4 4 5% 5% 7% 11% 48%	2800
July	1st to 10th	Day	10% 4 2 5% 4 4 5% 4 6% 9% 47%	6360
	11th to 20th	Day	5% 5% 3 6% 5% 6% 6% 5% 8% 12% 40%	6360
	21st to end	Day	6% 5% 2 7% 5% 5% 6% 5% 7% 11% 40%	6615
August	1st to 10th	Day	4 3 2 5% 4 4 5% 4 7% 9% 52%	4173
	11th to 20th	Day	11% 5% 2 5% 4 5% 4 4 7% 10% 43%	3849
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 9% 51%	4312
September	1st to 10th	Day	12% 5% 2 4 4 4 4 4 5% 7% 49%	2400
	11th to 20th	Day	9% 5% 2 5% 5% 4 4 3 6% 8% 50%	2360
	21st to end	Day	8% 4 2 5% 4 4 4 3 6% 8% 51%	2200
October	1st to 10th	Day	8% 4 2 5% 4 3 4 2 4 6% 57%	2020
	11th to 20th	Day	12% 5% 2 4 4 3 3 2 5% 6% 53%	2000
	21st to end	Day	17% 8% 2 5% 3 2 3 2 4 5% 47%	2165
November	1st to 10th	Day	10% 6% 2 4 4 4 3 3 5% 6% 54%	1852
	11th to 20th	Day	14% 7% 2 6% 4 3 4 3 5% 8% 45%	1890
	21st to end	Day	15% 10% 3 6% 5% 3 4 3 4 5% 41%	1846
December	1st to 10th	Day	9% 9% 3 6% 4 3 4 3 4 6% 49%	2690
	11th to 20th	Day	13% 8% 3 9% 5% 4 4 4 5% 6% 39%	3088
	21st to end	Day	23% 15% 5% 9% 5% 4 4 3 4 4 24%	4070
January	1st to 10th	Night	13% 9% 4 10% 5% 4 4 3 5% 5% 37%	8232
	11th to 20th	Night	9% 9% 3 8% 5% 6% 5% 3 4 5% 42%	7920
	21st to end	Night	16% 11% 3 8% 5% 4 3 3 4 6% 36%	8402
February	1st to 10th	Night	15% 10% 4 8% 5% 3 4 3 5% 4 37%	2722
	11th to 20th	Night	15% 8% 3 7% 5% 4 3 3 5% 6% 41%	2399
	21st to end	Night	15% 9% 3 7% 4 4 4 3 5% 5% 41%	1980
March	1st to 10th	Night	16% 11% 3 5% 4 4 4 3 4 5% 42%	5373
	11th to 20th	Night	11% 8% 3 5% 3 3 4 3 5% 6% 50%	4990
	21st to end	Night	16% 8% 3 8% 5% 5% 4 4 5% 6% 35%	5132
April	1st to 10th	Night	12% 6% 2 6% 4 3 4 4 5% 6% 47%	2000
	11th to 20th	Night	13% 7% 2 5% 4 5% 4 4 5% 7% 45%	1975
	21st to end	Night	19% 8% 3 6% 5% 2 3 4 5% 5% 41%	2000
May	1st to 10th	Night	16% 8% 2 6% 5% 5% 5% 4 6% 9% 34%	4314
	11th to 20th	Night	12% 8% 2 5% 4 4 5% 5% 6% 7% 42%	3730
	21st to end	Night	13% 7% 3 7% 5% 4 4 4 6% 8% 39%	3942
June	1st to 10th	Night	8% 4 2 6% 4 4 5% 4 7% 9% 47%	1600
	11th to 20th	Night	5% 5% 2 5% 3 4 4 5% 6% 9% 54%	1600
	21st to end	Night	4 4 2 4 4 4 5% 4 8% 10% 53%	1600
July	1st to 10th	Night	10% 5% 2 6% 4 3 4 3 6% 9% 48%	3618
	11th to 20th	Night	6% 4 2 6% 4 5% 5% 4 7% 10% 46%	3617
	21st to end	Night	6% 5% 2 7% 5% 5% 6% 5% 8% 12% 39%	4253
August	1st to 10th	Night	4 3 1 4 3 4 4 4 6% 9% 57%	2981
	11th to 20th	Night	9% 5% 2 6% 4 4 5% 4 6% 8% 46%	3200
	21st to end	Night	5% 3 1 4 3 3 4 3 6% 9% 58%	3586
September	1st to 10th	Night	11% 5% 2 5% 4 3 4 3 5% 7% 53%	2000
	11th to 20th	Night	7% 5% 2 5% 4 4 5% 3 6% 7% 52%	2020
	21st to end	Night	10% 4 2 4 4 4 4 3 5% 7% 53%	2200
October	1st to 10th	Night	7% 4 2 5% 3 3 3 3 4 7% 59%	2375
	11th to 20th	Night	12% 6% 2 5% 2 2 3 2 4 7% 55%	2400
	21st to end	Night	18% 7% 2 4 3 3 3 2 4 6% 47%	2673
November	1st to 10th	Night	11% 5% 2 5% 3 3 3 3 5% 4 56%	2666
	11th to 20th	Night	13% 6% 2 5% 3 4 3 3 4 6% 49%	2730
	21st to end	Night	17% 10% 4 5% 4 2 3 3 4 6% 43%	2771
December	1st to 10th	Night	13% 9% 3 7% 4 3 3 3 5% 6% 45%	4720
	11th to 20th	Night	14% 7% 3 6% 4 4 4 3 5% 6% 43%	5339
	21st to end	Night	23% 15% 4 9% 5% 4 4 3 4 5% 24%	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	50% 5% 12% 24% 8% 1	4692
	11th to 20th	Day	38% 5% 10% 26% 18% 3	5052
	21st to end	Day	50% 4 11% 16% 14% 5%	5812
February	1st to 10th	Day	49% 4 13% 23% 10% 1	1896
	11th to 20th	Day	49% 5% 9% 20% 14% 3	2008
	21st to end	Day	44% 5% 9% 22% 16% 3	1650
March	1st to 10th	Day	41% 3 5% 23% 24% 4	4498
	11th to 20th	Day	32% 4 9% 26% 23% 5%	4980
	21st to end	Day	42% 7% 14% 27% 9% 1	5785
April	1st to 10th	Day	39% 6% 12% 26% 17% 1	2400
	11th to 20th	Day	44% 4 11% 24% 14% 3	2374
	21st to end	Day	46% 6% 12% 23% 12% 1	2400
May	1st to 10th	Day	45% 9% 13% 21% 11%	5614
	11th to 20th	Day	44% 8% 11% 23% 13% 1	6179
	21st to end	Day	39% 8% 10% 22% 19% 1	6949
June	1st to 10th	Day	33% 8% 13% 27% 17% 3	2800
	11th to 20th	Day	28% 7% 13% 26% 23% 2	2800
	21st to end	Day	27% 8% 18% 25% 16% 5%	2800
July	1st to 10th	Day	33% 7% 10% 30% 19% 2	6291
	11th to 20th	Day	33% 10% 16% 27% 12% 2	6285
	21st to end	Day	34% 10% 17% 28% 11% 1	6428
August	1st to 10th	Day	25% 8% 15% 37% 15%	4159
	11th to 20th	Day	35% 7% 14% 26% 17% 1	3885
	21st to end	Day	28% 6% 14% 34% 15% 3	4311
September	1st to 10th	Day	33% 7% 10% 25% 20% 5%	2400
	11th to 20th	Day	33% 6% 9% 26% 24% 3	2360
	21st to end	Day	30% 6% 9% 26% 26% 3	2200
October	1st to 10th	Day	18% 3 5% 21% 44% 9%	3293
	11th to 20th	Day	22% 3 8% 21% 36% 9%	3240
	21st to end	Day	32% 3 7% 27% 28% 4	3479
November	1st to 10th	Day	31% 4 13% 27% 19% 5%	1852
	11th to 20th	Day	38% 5% 8% 24% 20% 6%	1890
	21st to end	Day	45% 4 9% 26% 15% 1	1846
December	1st to 10th	Day	35% 5% 13% 31% 16%	2690
	11th to 20th	Day	45% 5% 11% 23% 15% 1	3085
	21st to end	Day	63% 5% 11% 13% 6% 1	4070
January	1st to 10th	Night	48% 5% 14% 24% 9%	8233
	11th to 20th	Night	42% 5% 6% 25% 19% 3	7920
	21st to end	Night	50% 4 11% 19% 15% 1	8402
February	1st to 10th	Night	50% 5% 10% 22% 12% 1	2722
	11th to 20th	Night	45% 4 10% 21% 17% 2	2400
	21st to end	Night	45% 4 10% 23% 14% 4	1980
March	1st to 10th	Night	44% 5% 6% 22% 21% 2	5373
	11th to 20th	Night	34% 5% 10% 23% 22% 6%	4990
	21st to end	Night	47% 7% 11% 23% 11% 1	5132
April	1st to 10th	Night	36% 5% 12% 27% 17% 3	2000
	11th to 20th	Night	38% 5% 11% 24% 18% 4	1975
	21st to end	Night	44% 5% 8% 24% 16% 2	2000
May	1st to 10th	Night	45% 9% 14% 19% 12% 1	4344
	11th to 20th	Night	39% 7% 14% 24% 15% 2	3731
	21st to end	Night	40% 8% 11% 23% 15% 3	3950
June	1st to 10th	Night	31% 8% 14% 26% 18% 4	1600
	11th to 20th	Night	25% 6% 13% 27% 25% 4	1600
	21st to end	Night	24% 8% 15% 28% 19% 7%	1600
July	1st to 10th	Night	32% 6% 10% 28% 21% 3	3580
	11th to 20th	Night	30% 9% 15% 31% 14% 2	3572
	21st to end	Night	33% 9% 19% 26% 11% 1	4129
August	1st to 10th	Night	22% 7% 17% 35% 18% 1	2971
	11th to 20th	Night	34% 7% 13% 25% 19% 2	3230
	21st to end	Night	22% 7% 14% 34% 20% 3	3586
September	1st to 10th	Night	31% 5% 10% 26% 21% 6%	2000
	11th to 20th	Night	30% 5% 9% 25% 26% 4	2020
	21st to end	Night	30% 6% 9% 22% 27% 5%	2200
October	1st to 10th	Night	16% 3 6% 17% 49% 9%	3882
	11th to 20th	Night	21% 3 7% 22% 39% 8%	3899
	21st to end	Night	31% 4 9% 24% 26% 6%	4309
November	1st to 10th	Night	31% 4 12% 25% 23% 6%	2666
	11th to 20th	Night	36% 3 8% 25% 23% 4	2730
	21st to end	Night	43% 4 9% 24% 18% 2	2771
December	1st to 10th	Night	40% 4 10% 30% 15% 1	4720
	11th to 20th	Night	41% 5% 13% 23% 18%	5341
	21st to end	Night	61% 6% 12% 14% 6% 1	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	21% 15% 34% 21% 8% 1	330
	11th to 20th	Day	20% 18% 41% 18% 3	330
	21st to end	Day	17% 15% 47% 15% 6%	363
February	1st to 10th	Day	20% 15% 39% 21% 5%	330
	11th to 20th	Day	25% 15% 37% 17% 5% 1	315
	21st to end	Day	20% 18% 34% 24% 3	249
March	1st to 10th	Day	17% 16% 42% 19% 6%	300
	11th to 20th	Day	26% 13% 37% 17% 5% 2	300
	21st to end	Day	25% 16% 31% 21% 6% 1	470
April	1st to 10th	Day	18% 12% 35% 24% 10% 1	500
	11th to 20th	Day	21% 13% 30% 22% 13% 1	492
	21st to end	Day	20% 12% 32% 22% 12% 1	500
May	1st to 10th	Day	14% 13% 27% 30% 14% 2	503
	11th to 20th	Day	16% 10% 24% 24% 19% 7%	659
	21st to end	Day	12% 5% 25% 33% 18% 8%	789
June	1st to 10th	Day	12% 4 18% 29% 26% 12%	730
	11th to 20th	Day	9% 2 17% 35% 27% 10%	730
	21st to end	Day	4 4 22% 36% 25% 10%	730
July	1st to 10th	Day	10% 3 11% 25% 29% 21%	721
	11th to 20th	Day	6% 3 11% 36% 31% 13%	718
	21st to end	Day	8% 2 10% 29% 37% 13%	794
August	1st to 10th	Day	7% 1 10% 33% 35% 13%	691
	11th to 20th	Day	10% 3 11% 25% 36% 15%	519
	21st to end	Day	10% 2 8% 24% 36% 20%	583
September	1st to 10th	Day	13% 2 13% 24% 35% 14%	530
	11th to 20th	Day	9% 2 8% 26% 36% 19%	530
	21st to end	Day	10% 6% 18% 27% 26% 13%	530
October	1st to 10th	Day	10% 3 21% 33% 23% 10%	350
	11th to 20th	Day	12% 13% 32% 26% 13% 5%	330
	21st to end	Day	25% 17% 26% 22% 9%	363
November	1st to 10th	Day	11% 9% 34% 26% 14% 5%	330
	11th to 20th	Day	14% 18% 32% 21% 14% 2	330
	21st to end	Day	25% 14% 28% 21% 10% 2	330
December	1st to 10th	Day	12% 17% 36% 23% 7% 5%	330
	11th to 20th	Day	21% 12% 36% 22% 7% 1	330
	21st to end	Day	25% 15% 39% 17% 4	363
January	1st to 10th	Night	18% 12% 39% 27% 4	1050
	11th to 20th	Night	20% 13% 39% 23% 4	1050
	21st to end	Night	18% 11% 41% 28% 2	1155
February	1st to 10th	Night	20% 12% 36% 29% 3	1042
	11th to 20th	Night	19% 14% 38% 27% 1	804
	21st to end	Night	19% 11% 42% 27% 1	660
March	1st to 10th	Night	20% 12% 36% 28% 4	800
	11th to 20th	Night	21% 9% 35% 30% 5%	610
	21st to end	Night	22% 9% 31% 32% 5%	660
April	1st to 10th	Night	15% 10% 38% 29% 8%	600
	11th to 20th	Night	17% 8% 32% 30% 12% 1	593
	21st to end	Night	23% 6% 33% 30% 8% 1	600
May	1st to 10th	Night	16% 6% 28% 39% 11% 1	600
	11th to 20th	Night	17% 4 24% 35% 19% 2	591
	21st to end	Night	10% 4 19% 43% 21% 3	650
June	1st to 10th	Night	9% 2 19% 42% 27% 2	600
	11th to 20th	Night	6% 1 17% 50% 25% 2	600
	21st to end	Night	4 2 18% 42% 32% 2	600
July	1st to 10th	Night	9% 2 8% 36% 39% 6%	585
	11th to 20th	Night	5% 1 10% 41% 39% 4	582
	21st to end	Night	7% 2 11% 39% 39% 4	657
August	1st to 10th	Night	7% 2 7% 42% 38% 3	597
	11th to 20th	Night	6% 1 10% 41% 39% 4	594
	21st to end	Night	7% 2 7% 37% 42% 6%	660
September	1st to 10th	Night	12% 3 10% 37% 33% 5%	600
	11th to 20th	Night	9% 1 11% 38% 35% 6%	620
	21st to end	Night	11% 5% 18% 33% 29% 4	800
October	1st to 10th	Night	8% 3 21% 37% 26% 5%	800
	11th to 20th	Night	14% 6% 30% 33% 16% 1	800
	21st to end	Night	21% 9% 31% 31% 8%	880
November	1st to 10th	Night	13% 5% 34% 37% 11%	820
	11th to 20th	Night	16% 8% 35% 31% 9% 1	840
	21st to end	Night	22% 9% 33% 28% 7%	881
December	1st to 10th	Night	21% 10% 32% 32% 5% 1	1050
	11th to 20th	Night	21% 8% 31% 33% 6%	1050
	21st to end	Night	22% 12% 36% 27% 3	1155

Page generated at 2026-02-13 00:42:12. Version ac07

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