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 2026-05-17.

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	15% 11% 4 9% 5% 5% 5% 4 5% 7% 31%	132140
	Night	15% 12% 4 10% 5% 4 4 4 5% 6% 30%	130638
Transparency	Day	51% 6% 12% 19% 11% 1	135759
	Night	52% 6% 11% 19% 11% 1	135078
Seeing	Day	20% 15% 28% 22% 12% 4	16939
	Night	20% 12% 28% 27% 12% 1	26614

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% 21% 6% 21% 5% 4 3 2 4 5% 13%	5258
	11th to 20th	Day	12% 21% 8% 17% 8% 6% 5% 2 3 4 14%	5280
	21st to end	Day	19% 18% 9% 13% 8% 6% 5% 3 3 3 13%	5780
February	1st to 10th	Day	17% 18% 5% 12% 6% 4 4 3 4 5% 22%	1890
	11th to 20th	Day	14% 14% 7% 15% 8% 5% 5% 4 4 4 20%	1942
	21st to end	Day	17% 14% 5% 12% 6% 4 5% 3 5% 6% 23%	1730
March	1st to 10th	Day	17% 13% 6% 12% 4 4 3 3 4 5% 27%	4858
	11th to 20th	Day	12% 12% 4 11% 5% 4 4 3 4 5% 35%	5090
	21st to end	Day	19% 14% 5% 9% 5% 4 4 3 4 6% 26%	5586
April	1st to 10th	Day	15% 13% 3 10% 5% 5% 4 3 6% 5% 30%	2330
	11th to 20th	Day	16% 12% 3 7% 5% 4 5% 3 5% 6% 33%	2702
	21st to end	Day	19% 10% 3 7% 4 4 4 3 4 7% 33%	2730
May	1st to 10th	Day	21% 9% 3 8% 5% 4 5% 3 5% 6% 29%	5992
	11th to 20th	Day	17% 9% 3 7% 5% 5% 5% 4 6% 8% 33%	5939
	21st to end	Day	17% 7% 3 7% 5% 4 5% 4 7% 7% 34%	6433
June	1st to 10th	Day	14% 7% 3 7% 4 5% 5% 3 7% 8% 38%	2710
	11th to 20th	Day	12% 6% 3 7% 6% 4 5% 4 6% 9% 38%	2856
	21st to end	Day	11% 5% 2 6% 5% 5% 6% 5% 7% 10% 40%	2860
July	1st to 10th	Day	9% 6% 3 7% 5% 5% 5% 4 6% 9% 42%	6232
	11th to 20th	Day	10% 6% 3 6% 4 5% 6% 5% 7% 11% 38%	5900
	21st to end	Day	11% 6% 2 7% 5% 4 5% 4 6% 8% 40%	6424
August	1st to 10th	Day	12% 7% 2 7% 5% 5% 5% 4 6% 9% 38%	4234
	11th to 20th	Day	11% 6% 3 6% 4 4 6% 5% 7% 10% 38%	4174
	21st to end	Day	9% 5% 2 6% 4 5% 6% 5% 6% 10% 41%	4646
September	1st to 10th	Day	13% 5% 2 5% 4 4 5% 3 6% 7% 44%	2247
	11th to 20th	Day	10% 6% 2 5% 5% 4 5% 3 6% 8% 45%	2200
	21st to end	Day	18% 9% 2 6% 4 4 4 3 6% 7% 38%	2200
October	1st to 10th	Day	12% 8% 2 6% 4 4 4 4 7% 7% 41%	2095
	11th to 20th	Day	17% 8% 3 7% 3 4 4 4 5% 5% 38%	2000
	21st to end	Day	20% 12% 3 7% 5% 4 4 4 5% 5% 30%	2157
November	1st to 10th	Day	13% 11% 4 8% 5% 4 4 3 5% 7% 37%	1852
	11th to 20th	Day	18% 15% 4 7% 5% 4 4 3 3 6% 30%	1890
	21st to end	Day	18% 18% 5% 9% 5% 5% 4 4 5% 6% 19%	1728
December	1st to 10th	Day	18% 16% 6% 15% 6% 4 4 3 4 4 19%	2680
	11th to 20th	Day	20% 19% 8% 11% 5% 4 3 3 3 5% 18%	3070
	21st to end	Day	23% 22% 7% 13% 6% 5% 4 3 3 4 11%	4445
January	1st to 10th	Night	15% 20% 8% 22% 6% 5% 3 3 3 3 12%	7635
	11th to 20th	Night	10% 20% 10% 17% 8% 5% 6% 4 4 4 13%	7680
	21st to end	Night	18% 17% 6% 12% 6% 5% 5% 3 4 5% 20%	8401
February	1st to 10th	Night	19% 15% 5% 12% 6% 6% 4 2 5% 4 22%	2730
	11th to 20th	Night	16% 15% 6% 10% 6% 5% 5% 4 5% 5% 22%	2563
	21st to end	Night	18% 15% 6% 12% 5% 5% 4 3 4 5% 24%	2076
March	1st to 10th	Night	21% 12% 5% 8% 4 4 3 2 4 5% 32%	5213
	11th to 20th	Night	12% 10% 3 7% 4 4 5% 4 6% 7% 39%	5090
	21st to end	Night	17% 11% 4 9% 4 4 4 3 5% 5% 32%	5588
April	1st to 10th	Night	16% 13% 3 7% 5% 4 4 4 6% 7% 30%	2299
	11th to 20th	Night	15% 11% 3 7% 5% 5% 5% 4 5% 7% 33%	1873
	21st to end	Night	16% 9% 3 7% 4 4 4 4 6% 7% 36%	1890
May	1st to 10th	Night	21% 12% 4 9% 5% 4 5% 4 6% 6% 26%	4123
	11th to 20th	Night	14% 8% 3 7% 5% 4 4 3 6% 8% 37%	4086
	21st to end	Night	16% 6% 2 6% 4 4 5% 4 6% 8% 39%	4421
June	1st to 10th	Night	10% 7% 3 6% 5% 5% 5% 4 5% 7% 44%	1680
	11th to 20th	Night	9% 5% 2 7% 5% 4 5% 6% 7% 9% 40%	1534
	21st to end	Night	10% 5% 1 6% 3 5% 5% 4 7% 11% 43%	1529
July	1st to 10th	Night	8% 5% 2 6% 5% 4 5% 5% 7% 9% 44%	3706
	11th to 20th	Night	9% 4 2 6% 5% 5% 5% 5% 7% 10% 42%	4057
	21st to end	Night	8% 6% 2 6% 4 4 5% 4 6% 9% 46%	4427
August	1st to 10th	Night	10% 7% 3 7% 4 4 4 4 6% 9% 42%	2915
	11th to 20th	Night	12% 7% 2 7% 4 4 4 4 5% 7% 45%	2875
	21st to end	Night	7% 5% 3 7% 4 5% 5% 4 7% 8% 45%	3223
September	1st to 10th	Night	10% 5% 2 6% 5% 4 5% 3 6% 6% 48%	2145
	11th to 20th	Night	9% 4 1 5% 4 3 4 3 6% 7% 54%	2200
	21st to end	Night	16% 7% 3 6% 4 5% 5% 4 4 6% 41%	2200
October	1st to 10th	Night	13% 5% 2 7% 4 4 4 3 5% 7% 45%	2305
	11th to 20th	Night	19% 7% 3 7% 5% 4 4 4 5% 6% 37%	2400
	21st to end	Night	23% 10% 3 6% 4 4 4 3 6% 6% 31%	2680
November	1st to 10th	Night	14% 9% 3 6% 4 4 4 5% 5% 7% 39%	2666
	11th to 20th	Night	16% 15% 4 9% 5% 5% 4 3 4 5% 30%	2730
	21st to end	Night	21% 16% 4 9% 4 5% 4 3 6% 6% 23%	2888
December	1st to 10th	Night	16% 16% 7% 12% 6% 5% 4 4 4 5% 20%	4720
	11th to 20th	Night	18% 20% 7% 11% 5% 4 4 3 5% 5% 19%	5345
	21st to end	Night	22% 20% 6% 12% 5% 5% 4 3 5% 5% 13%	6745

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	75% 5% 10% 8% 2	5259
	11th to 20th	Day	75% 5% 8% 6% 6%	5280
	21st to end	Day	77% 3 6% 10% 3	5780
February	1st to 10th	Day	64% 5% 11% 13% 6%	1890
	11th to 20th	Day	66% 6% 9% 13% 5% 1	1951
	21st to end	Day	60% 6% 14% 13% 6% 1	1730
March	1st to 10th	Day	59% 5% 9% 20% 6%	4858
	11th to 20th	Day	49% 7% 14% 23% 7% 1	5090
	21st to end	Day	58% 6% 9% 17% 10%	5586
April	1st to 10th	Day	53% 7% 12% 17% 11% 1	2330
	11th to 20th	Day	51% 6% 12% 17% 12% 2	2702
	21st to end	Day	50% 6% 11% 21% 10% 2	2730
May	1st to 10th	Day	54% 7% 10% 17% 11% 2	6027
	11th to 20th	Day	47% 8% 13% 20% 11% 1	5943
	21st to end	Day	45% 8% 12% 20% 12% 3	6447
June	1st to 10th	Day	42% 8% 11% 25% 14% 1	2710
	11th to 20th	Day	42% 9% 14% 20% 14% 2	2856
	21st to end	Day	36% 9% 14% 22% 16% 2	2860
July	1st to 10th	Day	37% 6% 11% 29% 16% 1	6165
	11th to 20th	Day	38% 6% 15% 25% 15% 1	5831
	21st to end	Day	39% 6% 13% 21% 20% 2	6240
August	1st to 10th	Day	41% 7% 16% 23% 13%	4221
	11th to 20th	Day	38% 8% 13% 31% 10% 1	4213
	21st to end	Day	37% 7% 15% 28% 11% 2	4646
September	1st to 10th	Day	37% 7% 15% 21% 16% 3	2247
	11th to 20th	Day	36% 7% 15% 24% 16% 2	2200
	21st to end	Day	45% 7% 11% 19% 18% 1	2200
October	1st to 10th	Day	31% 6% 14% 29% 19% 1	3407
	11th to 20th	Day	44% 6% 10% 20% 19% 1	3240
	21st to end	Day	42% 5% 12% 23% 17% 1	3459
November	1st to 10th	Day	47% 5% 12% 21% 14% 1	1852
	11th to 20th	Day	56% 5% 11% 17% 9% 2	1890
	21st to end	Day	63% 7% 12% 13% 6%	1728
December	1st to 10th	Day	67% 6% 12% 13% 3	2680
	11th to 20th	Day	70% 5% 9% 13% 4	3066
	21st to end	Day	78% 5% 7% 8% 2	4445
January	1st to 10th	Night	76% 5% 7% 10% 3	7636
	11th to 20th	Night	74% 5% 7% 8% 5%	7680
	21st to end	Night	66% 4 10% 13% 6%	8401
February	1st to 10th	Night	65% 5% 11% 14% 5% 1	2730
	11th to 20th	Night	62% 7% 9% 15% 6%	2565
	21st to end	Night	62% 5% 10% 13% 7% 2	2076
March	1st to 10th	Night	55% 5% 12% 20% 8%	5213
	11th to 20th	Night	41% 8% 15% 25% 10% 1	5090
	21st to end	Night	50% 8% 9% 21% 13% 1	5588
April	1st to 10th	Night	52% 6% 12% 16% 12% 2	2299
	11th to 20th	Night	48% 7% 12% 16% 14% 3	1873
	21st to end	Night	46% 6% 12% 20% 14% 2	1890
May	1st to 10th	Night	57% 7% 10% 13% 9% 4	4150
	11th to 20th	Night	42% 9% 12% 22% 14% 1	4087
	21st to end	Night	40% 7% 14% 23% 13% 3	4429
June	1st to 10th	Night	38% 8% 11% 24% 16% 3	1680
	11th to 20th	Night	36% 9% 15% 22% 17% 2	1534
	21st to end	Night	34% 9% 14% 26% 15% 3	1529
July	1st to 10th	Night	34% 6% 15% 24% 16% 4	3666
	11th to 20th	Night	36% 7% 15% 26% 14% 2	4006
	21st to end	Night	33% 5% 14% 20% 25% 2	4297
August	1st to 10th	Night	38% 7% 14% 24% 15% 1	2904
	11th to 20th	Night	37% 7% 12% 29% 14% 1	2902
	21st to end	Night	34% 7% 14% 28% 14% 2	3223
September	1st to 10th	Night	34% 7% 13% 26% 16% 4	2145
	11th to 20th	Night	28% 7% 12% 29% 22% 2	2200
	21st to end	Night	42% 8% 11% 19% 18% 1	2200
October	1st to 10th	Night	30% 5% 9% 30% 25% 1	3773
	11th to 20th	Night	44% 5% 10% 20% 20% 1	3899
	21st to end	Night	40% 5% 10% 26% 17% 2	4316
November	1st to 10th	Night	43% 6% 13% 22% 14% 2	2666
	11th to 20th	Night	55% 6% 11% 17% 9% 2	2730
	21st to end	Night	61% 6% 12% 15% 5%	2888
December	1st to 10th	Night	64% 6% 11% 15% 4	4720
	11th to 20th	Night	67% 6% 11% 14% 3	5348
	21st to end	Night	72% 7% 10% 10% 2	6745

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% 22% 33% 11% 4 1	330
	11th to 20th	Day	31% 28% 31% 6% 3	330
	21st to end	Day	29% 28% 31% 12% 1 1	363
February	1st to 10th	Day	30% 23% 34% 11% 2	330
	11th to 20th	Day	30% 25% 33% 10% 2	330
	21st to end	Day	28% 30% 34% 8%	273
March	1st to 10th	Day	26% 21% 35% 13% 4	452
	11th to 20th	Day	27% 19% 32% 17% 5%	540
	21st to end	Day	30% 19% 30% 17% 4 1	594
April	1st to 10th	Day	25% 20% 32% 16% 7% 1	540
	11th to 20th	Day	25% 21% 26% 18% 7% 3	532
	21st to end	Day	26% 16% 32% 17% 9% 2	540
May	1st to 10th	Day	26% 17% 30% 20% 5% 2	543
	11th to 20th	Day	20% 11% 33% 23% 10% 4	551
	21st to end	Day	15% 10% 27% 26% 17% 4	573
June	1st to 10th	Day	14% 9% 30% 31% 14% 2	530
	11th to 20th	Day	14% 9% 26% 33% 16% 2	586
	21st to end	Day	10% 10% 29% 32% 15% 4	730
July	1st to 10th	Day	10% 5% 23% 29% 22% 11%	673
	11th to 20th	Day	12% 5% 25% 29% 20% 9%	524
	21st to end	Day	10% 6% 21% 33% 22% 9%	576
August	1st to 10th	Day	10% 5% 20% 31% 25% 10%	526
	11th to 20th	Day	13% 5% 24% 25% 23% 10%	519
	21st to end	Day	10% 7% 19% 30% 23% 12%	583
September	1st to 10th	Day	14% 6% 23% 23% 21% 12%	530
	11th to 20th	Day	10% 4 16% 27% 28% 15%	530
	21st to end	Day	20% 12% 24% 21% 15% 8%	530
October	1st to 10th	Day	11% 11% 26% 26% 19% 7%	530
	11th to 20th	Day	18% 17% 32% 22% 8% 3	530
	21st to end	Day	26% 20% 31% 18% 4	540
November	1st to 10th	Day	20% 22% 33% 16% 7% 2	330
	11th to 20th	Day	30% 24% 26% 13% 6% 1	330
	21st to end	Day	30% 22% 36% 11%	245
December	1st to 10th	Day	22% 26% 33% 14% 3 1	220
	11th to 20th	Day	27% 26% 34% 11% 2	220
	21st to end	Day	30% 23% 34% 11% 2	336
January	1st to 10th	Night	27% 21% 32% 16% 4	840
	11th to 20th	Night	29% 20% 31% 15% 4	840
	21st to end	Night	26% 18% 33% 20% 3	924
February	1st to 10th	Night	27% 17% 33% 21% 3	840
	11th to 20th	Night	25% 20% 32% 20% 3	823
	21st to end	Night	27% 17% 35% 18% 2	692
March	1st to 10th	Night	24% 15% 34% 22% 5%	840
	11th to 20th	Night	21% 17% 33% 23% 5% 1	840
	21st to end	Night	25% 11% 33% 23% 7% 1	924
April	1st to 10th	Night	23% 15% 33% 24% 4	840
	11th to 20th	Night	21% 12% 33% 25% 8% 1	629
	21st to end	Night	19% 10% 35% 30% 6% 1	630
May	1st to 10th	Night	21% 10% 28% 32% 8% 1	630
	11th to 20th	Night	19% 8% 27% 32% 13% 2	609
	21st to end	Night	12% 5% 22% 38% 22% 2	650
June	1st to 10th	Night	11% 4 28% 42% 14% 1	480
	11th to 20th	Night	10% 3 28% 43% 16% 1	400
	21st to end	Night	10% 3 25% 39% 21% 1	529
July	1st to 10th	Night	10% 2 15% 41% 29% 2	585
	11th to 20th	Night	9% 3 18% 43% 24% 3	582
	21st to end	Night	9% 2 17% 41% 28% 2	657
August	1st to 10th	Night	9% 2 15% 44% 27% 3	597
	11th to 20th	Night	9% 5% 16% 38% 28% 4	594
	21st to end	Night	8% 4 17% 36% 32% 3	660
September	1st to 10th	Night	12% 5% 17% 36% 26% 4	795
	11th to 20th	Night	10% 3 13% 35% 33% 5%	800
	21st to end	Night	17% 9% 23% 30% 20% 3	800
October	1st to 10th	Night	15% 9% 22% 33% 19% 2	800
	11th to 20th	Night	21% 13% 29% 26% 9% 1	800
	21st to end	Night	28% 13% 30% 24% 5%	880
November	1st to 10th	Night	20% 12% 34% 24% 9% 1	820
	11th to 20th	Night	26% 16% 33% 19% 6% 1	840
	21st to end	Night	30% 16% 31% 18% 5%	840
December	1st to 10th	Night	29% 17% 32% 18% 4	840
	11th to 20th	Night	26% 17% 37% 17% 3	840
	21st to end	Night	29% 17% 34% 18% 2	924

Page generated at 2026-05-14 01:58:58. Version ac07

Copyright © 2026 Attilla Danko.