LaGrange
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the LaGrange clear sky chart from 2005-11-06 to 2024-08-15.

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	15% 11% 4 8% 5% 4 5% 4 5% 7% 31%	95433
	Night	16% 12% 4 8% 5% 4 4 4 5% 6% 32%	93189
Transparency	Day	51% 7% 12% 18% 11% 1	95203
	Night	51% 7% 12% 18% 10% 1	93024
Seeing	Day	19% 14% 28% 22% 12% 4	14673
	Night	20% 11% 28% 27% 12% 1	24272

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	19% 23% 7% 14% 5% 4 4 2 4 5% 14%	2836
	11th to 20th	Day	15% 24% 8% 12% 6% 6% 6% 3 4 5% 12%	2840
	21st to end	Day	27% 20% 12% 12% 7% 3 2 2 3 3 8%	3124
February	1st to 10th	Day	17% 19% 5% 11% 6% 5% 4 3 4 5% 22%	1710
	11th to 20th	Day	14% 14% 7% 15% 8% 5% 5% 3 4 4 20%	1752
	21st to end	Day	18% 14% 4 12% 6% 4 4 3 5% 6% 23%	1570
March	1st to 10th	Day	21% 15% 6% 9% 4 4 3 3 4 6% 25%	3308
	11th to 20th	Day	13% 14% 5% 11% 5% 4 4 3 3 5% 33%	3480
	21st to end	Day	20% 13% 6% 9% 5% 4 4 3 4 6% 28%	3815
April	1st to 10th	Day	14% 14% 3 9% 5% 5% 4 4 6% 6% 31%	2108
	11th to 20th	Day	17% 12% 3 6% 5% 4 4 3 5% 6% 33%	2442
	21st to end	Day	20% 10% 3 7% 4 4 4 3 4 6% 33%	2470
May	1st to 10th	Day	19% 9% 3 8% 5% 4 5% 3 6% 6% 30%	4082
	11th to 20th	Day	18% 8% 3 6% 5% 4 5% 4 6% 8% 34%	4081
	21st to end	Day	10% 6% 3 7% 5% 5% 5% 5% 8% 8% 39%	4476
June	1st to 10th	Day	13% 7% 3 7% 4 5% 5% 3 7% 8% 37%	2574
	11th to 20th	Day	12% 6% 3 7% 6% 4 5% 4 6% 9% 39%	2713
	21st to end	Day	11% 5% 2 6% 5% 5% 5% 5% 7% 10% 40%	2717
July	1st to 10th	Day	10% 6% 3 7% 5% 5% 5% 4 7% 10% 39%	4354
	11th to 20th	Day	9% 5% 2 5% 4 5% 5% 4 6% 10% 44%	4120
	21st to end	Day	10% 7% 2 7% 5% 5% 6% 5% 7% 7% 40%	4466
August	1st to 10th	Day	9% 6% 3 7% 5% 6% 5% 4 7% 8% 40%	2457
	11th to 20th	Day	11% 6% 3 6% 5% 5% 6% 5% 7% 10% 37%	2357
	21st to end	Day	11% 6% 2 6% 5% 5% 6% 5% 6% 9% 41%	2560
September	1st to 10th	Day	14% 6% 2 6% 4 5% 6% 4 6% 7% 41%	2023
	11th to 20th	Day	11% 7% 2 5% 5% 4 5% 3 7% 8% 42%	1980
	21st to end	Day	17% 8% 2 6% 4 4 4 3 6% 7% 39%	1980
October	1st to 10th	Day	13% 8% 2 7% 5% 5% 4 4 7% 7% 38%	1886
	11th to 20th	Day	18% 9% 3 8% 3 4 5% 4 6% 5% 36%	1800
	21st to end	Day	21% 13% 3 7% 5% 4 4 4 5% 5% 28%	1942
November	1st to 10th	Day	12% 11% 3 8% 5% 4 4 3 5% 6% 37%	1672
	11th to 20th	Day	17% 15% 4 8% 5% 4 4 3 3 6% 30%	1710
	21st to end	Day	17% 17% 5% 9% 5% 5% 4 4 5% 6% 20%	1564
December	1st to 10th	Day	17% 20% 6% 12% 6% 5% 4 2 5% 4 18%	1520
	11th to 20th	Day	16% 18% 8% 14% 6% 4 4 3 4 6% 17%	1910
	21st to end	Day	22% 24% 7% 12% 6% 5% 3 3 4 5% 10%	3034
January	1st to 10th	Night	16% 23% 8% 13% 5% 4 3 3 4 4 16%	4109
	11th to 20th	Night	13% 22% 10% 16% 6% 5% 7% 4 3 3 10%	4120
	21st to end	Night	27% 20% 7% 13% 5% 3 3 2 3 3 15%	4532
February	1st to 10th	Night	20% 15% 5% 11% 6% 5% 4 2 5% 5% 21%	2470
	11th to 20th	Night	16% 16% 6% 10% 6% 6% 5% 4 5% 5% 22%	2313
	21st to end	Night	19% 14% 5% 12% 6% 5% 4 2 4 5% 24%	1884
March	1st to 10th	Night	21% 14% 5% 6% 4 3 3 2 4 5% 33%	3543
	11th to 20th	Night	14% 10% 3 7% 4 4 4 4 6% 7% 36%	3480
	21st to end	Night	18% 11% 3 9% 4 4 4 3 5% 6% 32%	3817
April	1st to 10th	Night	15% 13% 3 7% 5% 5% 4 4 6% 7% 32%	2081
	11th to 20th	Night	16% 11% 3 7% 5% 4 5% 4 6% 7% 34%	1693
	21st to end	Night	16% 9% 3 7% 4 4 4 4 6% 7% 36%	1710
May	1st to 10th	Night	20% 10% 4 8% 5% 5% 5% 3 6% 7% 27%	2813
	11th to 20th	Night	16% 8% 3 7% 4 4 4 3 6% 8% 36%	2812
	21st to end	Night	9% 5% 2 5% 3 4 4 4 7% 10% 47%	3079
June	1st to 10th	Night	10% 7% 2 6% 5% 5% 5% 4 5% 8% 43%	1596
	11th to 20th	Night	9% 5% 2 7% 5% 4 5% 5% 7% 9% 41%	1458
	21st to end	Night	10% 5% 2 6% 3 5% 5% 4 6% 11% 43%	1452
July	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 6% 9% 47%	2592
	11th to 20th	Night	9% 4 2 5% 4 4 5% 4 6% 9% 48%	2840
	21st to end	Night	7% 5% 2 6% 5% 4 5% 4 7% 10% 44%	3087
August	1st to 10th	Night	7% 5% 2 6% 3 4 5% 4 6% 9% 47%	1701
	11th to 20th	Night	8% 6% 1 6% 4 4 5% 4 6% 8% 46%	1643
	21st to end	Night	8% 6% 3 5% 4 5% 5% 4 6% 9% 46%	1782
September	1st to 10th	Night	11% 5% 2 6% 5% 4 5% 3 6% 7% 45%	1929
	11th to 20th	Night	10% 4 2 5% 4 3 4 3 6% 7% 51%	1980
	21st to end	Night	14% 6% 3 6% 4 5% 5% 4 4 6% 42%	1980
October	1st to 10th	Night	14% 6% 2 7% 5% 4 4 3 5% 8% 43%	2074
	11th to 20th	Night	20% 7% 3 8% 5% 4 4 4 5% 6% 35%	2160
	21st to end	Night	24% 10% 3 7% 4 4 4 3 6% 5% 29%	2412
November	1st to 10th	Night	15% 10% 3 6% 4 4 4 5% 5% 7% 38%	2406
	11th to 20th	Night	16% 15% 5% 9% 5% 4 4 3 4 5% 30%	2470
	21st to end	Night	21% 15% 4 9% 5% 5% 4 3 5% 6% 23%	2612
December	1st to 10th	Night	20% 18% 7% 9% 5% 4 4 4 4 5% 20%	2660
	11th to 20th	Night	17% 17% 6% 11% 5% 4 4 4 5% 5% 22%	3285
	21st to end	Night	24% 21% 6% 10% 5% 4 5% 3 4 5% 12%	4614

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	73% 6% 10% 9% 2	2837
	11th to 20th	Day	75% 6% 9% 8% 2	2840
	21st to end	Day	83% 4 6% 5% 2	3124
February	1st to 10th	Day	65% 5% 11% 13% 6%	1710
	11th to 20th	Day	65% 7% 9% 13% 5% 1	1761
	21st to end	Day	60% 7% 14% 12% 6% 2	1570
March	1st to 10th	Day	60% 6% 9% 20% 4	3308
	11th to 20th	Day	52% 8% 13% 21% 6% 1	3480
	21st to end	Day	56% 7% 11% 16% 9% 1	3815
April	1st to 10th	Day	52% 7% 12% 17% 11% 1	2108
	11th to 20th	Day	51% 6% 12% 17% 13% 2	2442
	21st to end	Day	50% 7% 11% 20% 10% 2	2470
May	1st to 10th	Day	51% 8% 11% 21% 8% 1	4120
	11th to 20th	Day	45% 9% 13% 23% 9% 1	4085
	21st to end	Day	37% 10% 14% 19% 15% 5%	4489
June	1st to 10th	Day	42% 8% 11% 25% 13% 1	2574
	11th to 20th	Day	40% 9% 15% 21% 14% 2	2713
	21st to end	Day	37% 9% 14% 22% 16% 2	2717
July	1st to 10th	Day	40% 6% 12% 23% 17% 2	4287
	11th to 20th	Day	33% 6% 14% 27% 18% 2	4051
	21st to end	Day	39% 7% 15% 16% 20% 2	4324
August	1st to 10th	Day	39% 9% 15% 23% 14%	2444
	11th to 20th	Day	39% 9% 16% 23% 11% 2	2357
	21st to end	Day	37% 9% 14% 22% 15% 3	2560
September	1st to 10th	Day	39% 8% 16% 19% 15% 3	2023
	11th to 20th	Day	38% 8% 15% 22% 15% 2	1980
	21st to end	Day	43% 7% 11% 20% 18% 1	1980
October	1st to 10th	Day	42% 8% 12% 22% 15% 1	1886
	11th to 20th	Day	48% 8% 12% 20% 12% 1	1800
	21st to end	Day	56% 7% 14% 14% 9% 1	1942
November	1st to 10th	Day	46% 5% 13% 20% 15% 1	1672
	11th to 20th	Day	55% 5% 11% 18% 8% 2	1710
	21st to end	Day	62% 7% 13% 12% 6%	1564
December	1st to 10th	Day	69% 7% 10% 12% 3	1520
	11th to 20th	Day	67% 7% 10% 13% 3	1906
	21st to end	Day	78% 6% 8% 6% 2	3034
January	1st to 10th	Night	70% 6% 9% 11% 4	4109
	11th to 20th	Night	78% 6% 8% 7% 2	4120
	21st to end	Night	75% 4 8% 9% 2	4532
February	1st to 10th	Night	65% 5% 11% 13% 5% 1	2470
	11th to 20th	Night	61% 8% 9% 15% 7%	2315
	21st to end	Night	63% 6% 9% 13% 8% 2	1884
March	1st to 10th	Night	54% 5% 12% 21% 8%	3543
	11th to 20th	Night	43% 10% 17% 19% 10% 1	3480
	21st to end	Night	48% 10% 9% 24% 8% 1	3817
April	1st to 10th	Night	50% 6% 13% 16% 12% 2	2081
	11th to 20th	Night	47% 8% 12% 16% 15% 3	1693
	21st to end	Night	46% 7% 12% 20% 14% 3	1710
May	1st to 10th	Night	53% 9% 10% 17% 9% 2	2840
	11th to 20th	Night	41% 10% 12% 21% 13% 2	2813
	21st to end	Night	30% 8% 15% 26% 17% 4	3087
June	1st to 10th	Night	38% 8% 11% 24% 15% 3	1596
	11th to 20th	Night	35% 8% 15% 22% 17% 2	1458
	21st to end	Night	34% 9% 13% 26% 15% 3	1452
July	1st to 10th	Night	35% 6% 13% 24% 17% 6%	2550
	11th to 20th	Night	31% 7% 14% 27% 18% 3	2786
	21st to end	Night	33% 7% 17% 19% 21% 2	2988
August	1st to 10th	Night	30% 9% 16% 25% 19% 1	1690
	11th to 20th	Night	33% 9% 17% 27% 13% 2	1643
	21st to end	Night	32% 9% 15% 23% 18% 3	1782
September	1st to 10th	Night	36% 8% 14% 23% 15% 4	1929
	11th to 20th	Night	30% 8% 13% 27% 21% 1	1980
	21st to end	Night	40% 8% 12% 20% 19% 1	1980
October	1st to 10th	Night	39% 7% 14% 20% 19% 1	2074
	11th to 20th	Night	48% 7% 12% 20% 13% 1	2160
	21st to end	Night	55% 6% 11% 18% 9% 1	2412
November	1st to 10th	Night	44% 7% 13% 20% 14% 2	2406
	11th to 20th	Night	55% 6% 11% 16% 10% 2	2470
	21st to end	Night	60% 6% 13% 15% 6%	2612
December	1st to 10th	Night	66% 7% 10% 12% 5%	2660
	11th to 20th	Night	61% 8% 13% 15% 3	3288
	21st to end	Night	73% 8% 10% 8% 2	4614

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	29% 23% 31% 11% 5% 1	270
	11th to 20th	Day	30% 27% 31% 8% 3	270
	21st to end	Day	29% 26% 31% 13% 1 1	297
February	1st to 10th	Day	32% 22% 33% 11% 2	270
	11th to 20th	Day	30% 25% 33% 10% 1	270
	21st to end	Day	30% 31% 31% 8%	225
March	1st to 10th	Day	27% 21% 34% 14% 5%	380
	11th to 20th	Day	26% 18% 33% 18% 5%	460
	21st to end	Day	31% 17% 29% 18% 4 1	506
April	1st to 10th	Day	22% 20% 33% 17% 7% 1	460
	11th to 20th	Day	25% 20% 25% 18% 7% 4	452
	21st to end	Day	26% 17% 32% 16% 8% 2	460
May	1st to 10th	Day	24% 15% 30% 22% 6% 3	463
	11th to 20th	Day	20% 10% 32% 22% 10% 5%	487
	21st to end	Day	13% 9% 27% 27% 19% 5%	529
June	1st to 10th	Day	13% 9% 30% 31% 15% 2	490
	11th to 20th	Day	13% 10% 25% 34% 16% 2	543
	21st to end	Day	11% 10% 30% 31% 14% 3	680
July	1st to 10th	Day	11% 5% 24% 29% 21% 11%	626
	11th to 20th	Day	12% 5% 25% 29% 20% 9%	484
	21st to end	Day	10% 5% 22% 33% 21% 8%	532
August	1st to 10th	Day	11% 5% 21% 31% 22% 10%	486
	11th to 20th	Day	14% 6% 24% 26% 21% 10%	456
	21st to end	Day	10% 7% 18% 30% 22% 12%	495
September	1st to 10th	Day	15% 6% 23% 24% 20% 12%	450
	11th to 20th	Day	11% 5% 18% 26% 26% 13%	450
	21st to end	Day	17% 14% 25% 21% 15% 8%	450
October	1st to 10th	Day	12% 11% 27% 25% 19% 6%	450
	11th to 20th	Day	19% 18% 33% 22% 7% 1	450
	21st to end	Day	29% 21% 30% 16% 4	457
November	1st to 10th	Day	18% 22% 33% 17% 8% 2	270
	11th to 20th	Day	27% 24% 27% 14% 7% 1	270
	21st to end	Day	25% 23% 39% 11%	201
December	1st to 10th	Day	22% 26% 33% 14% 3 2	180
	11th to 20th	Day	24% 27% 38% 11% 1	180
	21st to end	Day	27% 24% 35% 11% 2	274
January	1st to 10th	Night	27% 22% 33% 15% 4	760
	11th to 20th	Night	30% 19% 30% 16% 4	760
	21st to end	Night	26% 16% 33% 21% 3	836
February	1st to 10th	Night	28% 17% 33% 20% 2	760
	11th to 20th	Night	25% 19% 32% 21% 3	743
	21st to end	Night	27% 17% 34% 19% 2	628
March	1st to 10th	Night	24% 15% 32% 24% 5%	760
	11th to 20th	Night	20% 17% 33% 24% 6% 1	760
	21st to end	Night	25% 10% 31% 25% 8% 1	836
April	1st to 10th	Night	21% 16% 33% 26% 5%	760
	11th to 20th	Night	22% 11% 33% 24% 9% 1	569
	21st to end	Night	18% 9% 36% 29% 6% 1	570
May	1st to 10th	Night	20% 10% 28% 32% 9% 2	570
	11th to 20th	Night	19% 7% 27% 32% 13% 2	561
	21st to end	Night	11% 4 22% 38% 23% 2	617
June	1st to 10th	Night	11% 4 28% 42% 15% 1	456
	11th to 20th	Night	10% 3 27% 43% 16% 1	380
	21st to end	Night	11% 3 26% 38% 20% 1	502
July	1st to 10th	Night	10% 2 15% 41% 29% 3	555
	11th to 20th	Night	9% 3 18% 42% 24% 3	552
	21st to end	Night	9% 2 17% 42% 28% 2	624
August	1st to 10th	Night	10% 2 16% 43% 26% 4	567
	11th to 20th	Night	8% 5% 16% 39% 28% 4	549
	21st to end	Night	9% 4 18% 34% 31% 4	594
September	1st to 10th	Night	13% 5% 16% 36% 25% 4	715
	11th to 20th	Night	12% 4 14% 36% 30% 5%	720
	21st to end	Night	16% 9% 23% 30% 19% 3	720
October	1st to 10th	Night	16% 9% 23% 31% 19% 3	720
	11th to 20th	Night	22% 14% 29% 26% 8% 1	720
	21st to end	Night	29% 14% 28% 24% 5%	792
November	1st to 10th	Night	20% 12% 32% 25% 10% 1	740
	11th to 20th	Night	25% 15% 33% 19% 6% 1	760
	21st to end	Night	29% 16% 31% 19% 6%	760
December	1st to 10th	Night	29% 17% 31% 18% 4	760
	11th to 20th	Night	26% 17% 37% 18% 3	760
	21st to end	Night	29% 16% 34% 18% 2	836

Page generated at 2024-08-12 09:52:47. Version ac07

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