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 2024-01-15.

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% 3 5% 5% 3 5% 5% 6% 8% 42%	74765
	Night	13% 7% 3 5% 5% 3 4 4 5% 7% 44%	75023
Transparency	Day	39% 6% 12% 24% 15% 3	74473
	Night	39% 6% 11% 24% 17% 3	74836
Seeing	Day	14% 7% 23% 26% 21% 8%	14447
	Night	16% 7% 27% 33% 16% 2	24397

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	13% 10% 4 8% 6% 4 4 4 5% 7% 36%	1517
	11th to 20th	Day	16% 9% 4 7% 6% 3 5% 5% 5% 7% 33%	1576
	21st to end	Day	13% 10% 6% 6% 6% 3 3 4 4 6% 38%	1782
February	1st to 10th	Day	17% 9% 5% 8% 4 3 4 4 4 7% 35%	1624
	11th to 20th	Day	17% 8% 4 7% 6% 3 4 5% 5% 6% 36%	1748
	21st to end	Day	15% 10% 3 7% 6% 3 5% 4 5% 6% 38%	1480
March	1st to 10th	Day	14% 7% 4 7% 6% 3 4 4 4 5% 42%	1804
	11th to 20th	Day	20% 10% 3 5% 5% 3 4 4 5% 5% 36%	1980
	21st to end	Day	20% 10% 5% 8% 7% 3 4 5% 5% 6% 29%	2304
April	1st to 10th	Day	11% 6% 3 6% 6% 3 5% 5% 5% 8% 44%	2160
	11th to 20th	Day	16% 7% 3 6% 5% 3 4 4 4 6% 41%	2134
	21st to end	Day	17% 7% 3 6% 5% 3 5% 4 5% 6% 38%	2160
May	1st to 10th	Day	16% 5% 3 6% 6% 3 5% 5% 6% 9% 36%	2222
	11th to 20th	Day	16% 5% 3 6% 4 3 5% 5% 6% 8% 41%	2419
	21st to end	Day	10% 5% 2 6% 6% 5% 6% 7% 6% 11% 38%	2725
June	1st to 10th	Day	8% 4 2 5% 5% 3 4 5% 6% 9% 47%	2520
	11th to 20th	Day	7% 3 2 4 5% 3 4 6% 7% 9% 50%	2520
	21st to end	Day	4 4 2 6% 5% 3 5% 6% 7% 11% 48%	2520
July	1st to 10th	Day	9% 3 2 4 5% 4 6% 7% 8% 10% 42%	2520
	11th to 20th	Day	4 3 2 4 5% 3 6% 7% 6% 11% 50%	2520
	21st to end	Day	7% 5% 2 5% 5% 3 6% 6% 6% 9% 47%	2627
August	1st to 10th	Day	7% 4 2 5% 5% 3 6% 6% 8% 10% 43%	2297
	11th to 20th	Day	9% 5% 3 4 6% 4 5% 6% 8% 10% 41%	2125
	21st to end	Day	8% 4 2 5% 5% 3 5% 5% 6% 9% 49%	2376
September	1st to 10th	Day	14% 6% 2 3 4 3 5% 4 5% 8% 47%	2160
	11th to 20th	Day	8% 5% 2 4 5% 3 5% 4 6% 7% 50%	2124
	21st to end	Day	7% 4 2 4 5% 3 4 5% 6% 8% 52%	1980
October	1st to 10th	Day	9% 4 2 4 4 3 4 4 4 6% 55%	1818
	11th to 20th	Day	13% 5% 2 4 4 3 4 3 5% 7% 51%	1800
	21st to end	Day	17% 7% 2 4 4 2 3 3 4 5% 47%	1949
November	1st to 10th	Day	10% 5% 2 3 4 3 3 3 5% 6% 55%	1672
	11th to 20th	Day	14% 6% 3 5% 5% 2 4 4 5% 8% 45%	1710
	21st to end	Day	15% 9% 3 6% 5% 3 4 3 4 5% 42%	1671
December	1st to 10th	Day	14% 10% 3 5% 6% 3 4 5% 5% 7% 39%	1520
	11th to 20th	Day	14% 9% 4 7% 6% 3 4 5% 4 6% 38%	1918
	21st to end	Day	20% 12% 5% 7% 6% 4 5% 4 4 5% 27%	2783
January	1st to 10th	Night	14% 9% 4 6% 6% 3 4 5% 5% 6% 39%	2648
	11th to 20th	Night	16% 11% 4 7% 6% 4 4 3 4 6% 37%	2469
	21st to end	Night	13% 9% 5% 7% 6% 4 4 4 5% 7% 36%	2574
February	1st to 10th	Night	17% 10% 5% 7% 5% 3 4 4 4 4 35%	2334
	11th to 20th	Night	15% 7% 4 6% 5% 3 4 3 4 6% 42%	2098
	21st to end	Night	17% 9% 3 7% 5% 3 4 3 5% 6% 38%	1776
March	1st to 10th	Night	15% 9% 3 5% 5% 3 4 3 5% 5% 43%	2160
	11th to 20th	Night	18% 8% 4 6% 5% 2 4 4 5% 5% 37%	1990
	21st to end	Night	18% 10% 3 6% 7% 4 4 5% 5% 6% 32%	2052
April	1st to 10th	Night	11% 5% 3 5% 5% 2 5% 5% 5% 6% 49%	1800
	11th to 20th	Night	13% 7% 3 4 5% 4 4 4 5% 7% 44%	1775
	21st to end	Night	19% 7% 3 6% 5% 2 3 4 4 5% 42%	1800
May	1st to 10th	Night	15% 6% 3 4 5% 2 5% 5% 5% 6% 43%	1736
	11th to 20th	Night	14% 8% 3 4 5% 2 4 5% 5% 7% 44%	1472
	21st to end	Night	9% 5% 3 6% 6% 4 5% 6% 7% 10% 40%	1551
June	1st to 10th	Night	7% 3 2 6% 5% 3 5% 5% 7% 9% 49%	1440
	11th to 20th	Night	5% 4 2 4 3 2 5% 5% 5% 9% 55%	1440
	21st to end	Night	4 3 2 4 4 3 5% 5% 8% 10% 53%	1440
July	1st to 10th	Night	8% 3 2 5% 5% 3 4 5% 7% 10% 49%	1440
	11th to 20th	Night	5% 3 2 4 4 3 4 4 6% 10% 55%	1440
	21st to end	Night	6% 4 2 5% 4 3 5% 5% 6% 11% 48%	1688
August	1st to 10th	Night	6% 3 1 5% 5% 3 5% 6% 7% 9% 51%	1638
	11th to 20th	Night	6% 4 1 5% 5% 3 5% 6% 7% 8% 49%	1776
	21st to end	Night	6% 3 2 4 4 3 4 4 5% 9% 56%	1980
September	1st to 10th	Night	12% 5% 2 4 4 3 3 3 4 7% 53%	1800
	11th to 20th	Night	7% 5% 2 4 4 3 5% 5% 6% 7% 52%	1818
	21st to end	Night	9% 4 2 3 4 3 4 4 5% 7% 55%	1980
October	1st to 10th	Night	8% 4 2 4 4 2 4 3 4 7% 57%	2137
	11th to 20th	Night	13% 6% 2 5% 3 2 3 3 4 8% 52%	2160
	21st to end	Night	19% 6% 3 4 4 2 4 2 4 6% 46%	2405
November	1st to 10th	Night	11% 5% 2 4 4 2 3 4 4 4 58%	2406
	11th to 20th	Night	14% 5% 3 5% 4 2 4 4 4 6% 50%	2470
	21st to end	Night	18% 8% 4 4 4 2 3 3 4 6% 45%	2507
December	1st to 10th	Night	16% 10% 4 6% 5% 3 4 4 6% 7% 36%	2660
	11th to 20th	Night	17% 7% 4 5% 5% 3 4 4 4 5% 42%	3279
	21st to end	Night	17% 15% 5% 9% 7% 4 5% 5% 5% 5% 24%	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	47% 5% 12% 21% 12% 1	1518
	11th to 20th	Day	50% 5% 11% 24% 8% 1	1576
	21st to end	Day	46% 5% 13% 23% 12% 2	1782
February	1st to 10th	Day	50% 4 12% 23% 10% 1	1624
	11th to 20th	Day	49% 5% 10% 20% 13% 3	1758
	21st to end	Day	47% 5% 10% 23% 13% 3	1480
March	1st to 10th	Day	44% 5% 9% 24% 15% 3	1804
	11th to 20th	Day	51% 5% 10% 18% 14% 2	1980
	21st to end	Day	55% 7% 12% 17% 8% 1	2304
April	1st to 10th	Day	37% 6% 13% 27% 17% 1	2160
	11th to 20th	Day	45% 5% 10% 24% 13% 3	2134
	21st to end	Day	47% 6% 11% 23% 12% 1	2160
May	1st to 10th	Day	45% 7% 14% 24% 10% 1	2222
	11th to 20th	Day	41% 8% 12% 23% 14% 2	2423
	21st to end	Day	39% 10% 14% 22% 13% 2	2725
June	1st to 10th	Day	32% 8% 13% 27% 17% 2	2520
	11th to 20th	Day	28% 7% 14% 25% 23% 3	2520
	21st to end	Day	28% 9% 17% 25% 16% 6%	2520
July	1st to 10th	Day	33% 10% 15% 26% 13% 4	2451
	11th to 20th	Day	26% 9% 15% 27% 20% 3	2445
	21st to end	Day	32% 9% 13% 29% 16% 2	2481
August	1st to 10th	Day	32% 10% 13% 28% 16%	2283
	11th to 20th	Day	35% 8% 14% 27% 14% 1	2125
	21st to end	Day	31% 7% 15% 24% 18% 5%	2376
September	1st to 10th	Day	35% 7% 10% 26% 17% 5%	2160
	11th to 20th	Day	33% 6% 9% 26% 23% 3	2124
	21st to end	Day	28% 7% 9% 27% 25% 3	1980
October	1st to 10th	Day	31% 5% 9% 26% 25% 4	1818
	11th to 20th	Day	34% 4 10% 24% 22% 6%	1800
	21st to end	Day	40% 4 8% 27% 17% 4	1949
November	1st to 10th	Day	30% 4 14% 27% 19% 6%	1672
	11th to 20th	Day	38% 5% 8% 24% 20% 5%	1710
	21st to end	Day	45% 4 9% 26% 16% 1	1671
December	1st to 10th	Day	43% 7% 12% 25% 13% 1	1520
	11th to 20th	Day	47% 5% 10% 22% 14% 2	1915
	21st to end	Day	58% 6% 10% 16% 8% 2	2783
January	1st to 10th	Night	46% 5% 10% 23% 15% 1	2648
	11th to 20th	Night	51% 4 9% 24% 12% 1	2469
	21st to end	Night	47% 4 13% 21% 13% 1	2574
February	1st to 10th	Night	52% 5% 9% 21% 11% 1	2334
	11th to 20th	Night	44% 4 11% 21% 17% 2	2099
	21st to end	Night	48% 4 11% 22% 12% 4	1776
March	1st to 10th	Night	44% 5% 9% 22% 17% 3	2160
	11th to 20th	Night	47% 6% 9% 21% 14% 3	1990
	21st to end	Night	52% 6% 12% 19% 9% 1	2052
April	1st to 10th	Night	35% 5% 12% 28% 18% 3	1800
	11th to 20th	Night	39% 5% 11% 23% 17% 4	1775
	21st to end	Night	45% 5% 7% 24% 17% 3	1800
May	1st to 10th	Night	42% 6% 11% 23% 16% 2	1736
	11th to 20th	Night	39% 6% 14% 23% 16% 2	1473
	21st to end	Night	37% 10% 13% 21% 16% 4	1552
June	1st to 10th	Night	30% 8% 14% 26% 18% 3	1440
	11th to 20th	Night	24% 7% 13% 27% 25% 4	1440
	21st to end	Night	24% 8% 14% 29% 18% 7%	1440
July	1st to 10th	Night	29% 7% 15% 28% 15% 5%	1400
	11th to 20th	Night	25% 7% 15% 28% 20% 5%	1392
	21st to end	Night	28% 8% 13% 30% 18% 3	1594
August	1st to 10th	Night	27% 8% 14% 32% 16% 2	1628
	11th to 20th	Night	30% 8% 13% 26% 21% 2	1776
	21st to end	Night	25% 7% 14% 26% 23% 5%	1980
September	1st to 10th	Night	32% 5% 10% 26% 20% 7%	1800
	11th to 20th	Night	30% 6% 10% 26% 25% 4	1818
	21st to end	Night	27% 6% 9% 23% 28% 5%	1980
October	1st to 10th	Night	27% 5% 11% 25% 27% 6%	2137
	11th to 20th	Night	32% 4 8% 27% 22% 7%	2160
	21st to end	Night	41% 4 9% 21% 21% 4	2405
November	1st to 10th	Night	30% 4 12% 25% 23% 6%	2406
	11th to 20th	Night	36% 3 8% 24% 23% 5%	2470
	21st to end	Night	42% 4 9% 25% 19% 2	2507
December	1st to 10th	Night	47% 5% 10% 23% 13% 1	2660
	11th to 20th	Night	44% 5% 10% 24% 16% 1	3281
	21st to end	Night	59% 7% 10% 15% 8% 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	21% 15% 31% 23% 9% 1	270
	11th to 20th	Day	26% 15% 37% 19% 3	252
	21st to end	Day	17% 16% 45% 16% 6%	264
February	1st to 10th	Day	23% 15% 40% 16% 5%	240
	11th to 20th	Day	26% 15% 35% 18% 5% 1	240
	21st to end	Day	24% 15% 33% 25% 4 1	198
March	1st to 10th	Day	19% 12% 45% 19% 5%	240
	11th to 20th	Day	30% 9% 35% 18% 5% 3	240
	21st to end	Day	27% 15% 29% 21% 7% 1	390
April	1st to 10th	Day	15% 11% 37% 25% 11% 2	420
	11th to 20th	Day	20% 12% 29% 24% 14% 1	412
	21st to end	Day	22% 12% 31% 20% 13% 1	420
May	1st to 10th	Day	15% 13% 26% 30% 13% 2	423
	11th to 20th	Day	17% 9% 24% 25% 19% 6%	565
	21st to end	Day	11% 3 24% 34% 19% 9%	679
June	1st to 10th	Day	11% 3 16% 29% 28% 13%	630
	11th to 20th	Day	8% 1 17% 34% 29% 10%	630
	21st to end	Day	4 4 22% 37% 24% 10%	630
July	1st to 10th	Day	10% 2 10% 24% 30% 24%	621
	11th to 20th	Day	5% 2 10% 35% 33% 14%	618
	21st to end	Day	9% 1 11% 30% 36% 12%	684
August	1st to 10th	Day	8% 2 8% 34% 35% 14%	595
	11th to 20th	Day	11% 2 10% 24% 38% 14%	439
	21st to end	Day	10% 1 8% 24% 36% 20%	495
September	1st to 10th	Day	15% 2 13% 21% 34% 14%	450
	11th to 20th	Day	8% 1 9% 28% 35% 19%	450
	21st to end	Day	8% 6% 18% 29% 26% 13%	450
October	1st to 10th	Day	12% 4 22% 34% 20% 7%	288
	11th to 20th	Day	13% 13% 36% 26% 10% 3	270
	21st to end	Day	26% 15% 26% 22% 10%	297
November	1st to 10th	Day	11% 7% 33% 27% 16% 6%	270
	11th to 20th	Day	14% 18% 30% 21% 16% 2	270
	21st to end	Day	24% 12% 30% 22% 11% 2	270
December	1st to 10th	Day	13% 15% 37% 21% 8% 6%	270
	11th to 20th	Day	22% 12% 34% 23% 8% 1	270
	21st to end	Day	25% 15% 38% 18% 4	297
January	1st to 10th	Night	19% 11% 38% 26% 5%	950
	11th to 20th	Night	21% 12% 38% 24% 5%	921
	21st to end	Night	17% 11% 40% 29% 3	990
February	1st to 10th	Night	22% 13% 35% 28% 2	894
	11th to 20th	Night	19% 14% 38% 28% 1	703
	21st to end	Night	21% 11% 40% 27% 1	592
March	1st to 10th	Night	21% 11% 37% 28% 4	720
	11th to 20th	Night	22% 8% 34% 30% 5%	550
	21st to end	Night	23% 8% 30% 33% 6%	594
April	1st to 10th	Night	14% 9% 39% 29% 9%	540
	11th to 20th	Night	17% 8% 31% 30% 13% 1	533
	21st to end	Night	23% 6% 34% 29% 8% 1	540
May	1st to 10th	Night	16% 5% 28% 39% 11% 1	540
	11th to 20th	Night	17% 4 24% 35% 19% 2	531
	21st to end	Night	10% 4 18% 43% 23% 4	584
June	1st to 10th	Night	9% 1 17% 41% 30% 2	540
	11th to 20th	Night	5% 17% 50% 26% 2	540
	21st to end	Night	5% 2 18% 43% 31% 2	540
July	1st to 10th	Night	9% 2 7% 36% 40% 7%	525
	11th to 20th	Night	5% 1 10% 41% 40% 4	522
	21st to end	Night	7% 1 11% 38% 38% 4	591
August	1st to 10th	Night	7% 2 6% 41% 40% 3	537
	11th to 20th	Night	7% 9% 40% 39% 4	534
	21st to end	Night	7% 2 7% 36% 41% 7%	594
September	1st to 10th	Night	13% 2 9% 37% 33% 6%	540
	11th to 20th	Night	9% 1 11% 38% 34% 6%	558
	21st to end	Night	10% 4 19% 33% 30% 4	720
October	1st to 10th	Night	9% 4 22% 36% 26% 4	720
	11th to 20th	Night	15% 7% 30% 32% 14% 1	720
	21st to end	Night	22% 9% 30% 31% 8%	792
November	1st to 10th	Night	13% 4 33% 37% 11%	740
	11th to 20th	Night	17% 9% 34% 31% 10% 1	760
	21st to end	Night	23% 8% 32% 30% 7%	797
December	1st to 10th	Night	21% 10% 31% 32% 6% 1	950
	11th to 20th	Night	22% 7% 29% 34% 7%	950
	21st to end	Night	22% 12% 36% 27% 4	1045

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