La Crosse
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the La Crosse clear sky chart from 2005-11-06 to 2025-07-06.

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	13% 9% 3 8% 5% 4 4 4 5% 7% 37%	120378
	Night	12% 10% 4 9% 5% 4 4 4 5% 6% 37%	118680
Transparency	Day	45% 5% 12% 24% 12% 1	123935
	Night	47% 5% 11% 23% 13% 1	123263
Seeing	Day	18% 12% 31% 24% 12% 3	16861
	Night	18% 10% 30% 30% 11% 1	26758

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	6% 12% 7% 20% 7% 7% 5% 3 5% 5% 23%	3617
	11th to 20th	Day	7% 12% 7% 11% 7% 4 8% 10% 8% 6% 20%	3620
	21st to end	Day	11% 15% 8% 11% 4 4 3 2 5% 5% 31%	4368
February	1st to 10th	Day	9% 13% 5% 11% 6% 4 5% 5% 5% 6% 31%	1800
	11th to 20th	Day	12% 11% 5% 8% 6% 5% 5% 4 5% 6% 34%	1769
	21st to end	Day	12% 12% 3 11% 6% 5% 4 3 5% 7% 34%	1650
March	1st to 10th	Day	14% 8% 3 5% 4 3 3 3 4 5% 49%	4567
	11th to 20th	Day	11% 7% 2 7% 4 4 5% 3 5% 8% 44%	4980
	21st to end	Day	23% 12% 3 8% 4 4 4 3 4 4 30%	5725
April	1st to 10th	Day	18% 13% 4 7% 5% 5% 3 3 5% 6% 32%	2400
	11th to 20th	Day	19% 13% 4 7% 4 4 4 3 5% 5% 32%	2374
	21st to end	Day	20% 11% 3 7% 5% 4 4 3 6% 6% 31%	2440
May	1st to 10th	Day	15% 8% 2 6% 4 4 4 3 5% 6% 43%	6305
	11th to 20th	Day	15% 7% 2 6% 4 4 4 4 5% 7% 41%	6319
	21st to end	Day	19% 7% 2 6% 4 4 4 4 5% 7% 38%	6935
June	1st to 10th	Day	12% 5% 2 5% 4 4 4 4 7% 8% 45%	2800
	11th to 20th	Day	13% 6% 2 6% 4 4 4 5% 6% 9% 40%	2800
	21st to end	Day	14% 6% 3 6% 5% 5% 5% 4 6% 9% 38%	2800
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 6% 5% 7% 9% 38%	4511
	11th to 20th	Day	5% 3 2 5% 3 4 5% 4 7% 9% 53%	4440
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 5% 7% 8% 42%	4813
August	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 4 6% 8% 42%	4200
	11th to 20th	Day	14% 6% 2 5% 4 3 4 3 6% 8% 45%	3991
	21st to end	Day	8% 5% 2 6% 5% 4 5% 4 7% 9% 44%	4180
September	1st to 10th	Day	15% 5% 2 5% 3 3 4 4 5% 7% 46%	2280
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 3 5% 7% 47%	2280
	21st to end	Day	13% 8% 3 6% 4 4 4 3 5% 7% 43%	2019
October	1st to 10th	Day	15% 8% 2 6% 4 3 4 3 5% 5% 45%	1900
	11th to 20th	Day	18% 10% 3 6% 3 3 4 3 5% 8% 37%	1900
	21st to end	Day	18% 11% 3 8% 5% 3 3 3 3 6% 37%	1989
November	1st to 10th	Day	14% 9% 3 8% 4 3 4 3 6% 6% 40%	1762
	11th to 20th	Day	14% 14% 4 10% 6% 4 3 4 5% 6% 30%	1644
	21st to end	Day	12% 12% 4 8% 5% 4 4 3 4 6% 38%	1600
December	1st to 10th	Day	7% 11% 5% 13% 8% 6% 4 4 6% 7% 30%	2610
	11th to 20th	Day	14% 17% 5% 11% 8% 5% 5% 4 6% 6% 21%	3008
	21st to end	Day	18% 20% 9% 17% 5% 4 3 3 4 3 13%	3982
January	1st to 10th	Night	7% 12% 7% 15% 8% 5% 4 3 5% 6% 28%	6348
	11th to 20th	Night	9% 14% 6% 14% 7% 6% 8% 8% 7% 4 18%	6360
	21st to end	Night	10% 17% 7% 10% 5% 5% 4 4 5% 5% 29%	6609
February	1st to 10th	Night	8% 15% 6% 10% 7% 5% 4 4 4 5% 32%	2600
	11th to 20th	Night	9% 10% 4 9% 5% 6% 5% 3 4 6% 38%	2517
	21st to end	Night	13% 12% 4 9% 6% 5% 4 3 5% 5% 36%	1980
March	1st to 10th	Night	12% 8% 4 7% 4 4 4 3 4 5% 44%	5327
	11th to 20th	Night	9% 9% 3 8% 4 4 4 4 5% 7% 43%	4980
	21st to end	Night	24% 14% 4 9% 4 3 3 2 4 5% 28%	5203
April	1st to 10th	Night	17% 11% 3 8% 4 3 4 3 5% 5% 37%	2000
	11th to 20th	Night	19% 11% 3 7% 3 3 4 3 5% 6% 36%	1975
	21st to end	Night	19% 10% 2 6% 5% 4 4 3 5% 6% 34%	1956
May	1st to 10th	Night	15% 7% 2 6% 4 3 4 3 5% 6% 44%	3608
	11th to 20th	Night	12% 6% 2 5% 4 4 3 3 5% 7% 50%	3596
	21st to end	Night	17% 7% 3 6% 4 4 4 3 6% 7% 39%	3942
June	1st to 10th	Night	11% 4 2 5% 4 5% 4 4 7% 8% 46%	1600
	11th to 20th	Night	10% 7% 3 7% 5% 4 4 3 6% 10% 42%	1600
	21st to end	Night	10% 5% 2 6% 4 3 4 3 6% 8% 50%	1600
July	1st to 10th	Night	11% 6% 2 6% 3 4 4 4 5% 8% 45%	2570
	11th to 20th	Night	5% 3 2 5% 3 3 4 3 6% 10% 57%	2530
	21st to end	Night	5% 5% 2 6% 4 4 5% 4 6% 9% 50%	2750
August	1st to 10th	Night	11% 4 2 5% 4 4 5% 4 5% 7% 48%	2736
	11th to 20th	Night	11% 5% 2 5% 2 3 3 3 5% 6% 53%	2846
	21st to end	Night	10% 7% 2 5% 3 4 5% 3 5% 7% 49%	3476
September	1st to 10th	Night	10% 5% 2 6% 3 4 4 3 4 7% 52%	1900
	11th to 20th	Night	12% 4 2 5% 3 3 3 3 5% 7% 53%	1900
	21st to end	Night	12% 5% 2 5% 3 3 3 3 5% 6% 54%	2137
October	1st to 10th	Night	14% 6% 2 5% 3 4 3 3 4 6% 51%	2280
	11th to 20th	Night	16% 8% 2 7% 4 4 4 3 5% 7% 41%	2280
	21st to end	Night	17% 10% 3 7% 4 4 4 3 5% 6% 36%	2608
November	1st to 10th	Night	14% 10% 3 7% 4 4 4 3 5% 5% 42%	2536
	11th to 20th	Night	12% 13% 6% 10% 6% 5% 4 3 5% 4 32%	2755
	21st to end	Night	14% 14% 4 10% 5% 4 3 3 4 5% 35%	2800
December	1st to 10th	Night	7% 8% 4 12% 8% 7% 5% 3 6% 7% 32%	4580
	11th to 20th	Night	13% 18% 7% 14% 5% 5% 5% 4 4 4 22%	5199
	21st to end	Night	18% 19% 8% 15% 5% 4 4 3 3 4 16%	6996

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	63% 4 10% 16% 6%	3618
	11th to 20th	Day	58% 5% 9% 16% 12%	3620
	21st to end	Day	56% 4 13% 17% 10%	4368
February	1st to 10th	Day	53% 5% 14% 16% 11% 1	1800
	11th to 20th	Day	51% 5% 11% 24% 8% 1	1778
	21st to end	Day	51% 5% 11% 22% 10% 2	1650
March	1st to 10th	Day	38% 3 13% 28% 15% 3	4567
	11th to 20th	Day	38% 3 15% 29% 12% 2	4980
	21st to end	Day	58% 4 10% 15% 11% 1	5727
April	1st to 10th	Day	54% 4 11% 20% 10% 1	2400
	11th to 20th	Day	54% 5% 9% 20% 11% 2	2374
	21st to end	Day	53% 6% 12% 18% 11% 1	2440
May	1st to 10th	Day	40% 4 8% 27% 18% 2	6343
	11th to 20th	Day	42% 7% 10% 26% 15% 2	6323
	21st to end	Day	45% 5% 9% 27% 12% 1	6949
June	1st to 10th	Day	35% 7% 14% 29% 14% 2	2800
	11th to 20th	Day	40% 8% 13% 24% 15% 1	2800
	21st to end	Day	42% 7% 14% 22% 13% 2	2800
July	1st to 10th	Day	40% 8% 17% 26% 8% 1	4442
	11th to 20th	Day	26% 7% 15% 33% 18% 1	4365
	21st to end	Day	36% 8% 13% 24% 18% 1	4662
August	1st to 10th	Day	37% 6% 13% 28% 14% 1	4185
	11th to 20th	Day	36% 6% 12% 33% 13%	4030
	21st to end	Day	34% 6% 15% 31% 13% 1	4179
September	1st to 10th	Day	37% 6% 14% 25% 18% 1	2280
	11th to 20th	Day	37% 7% 13% 31% 12% 1	2280
	21st to end	Day	39% 6% 11% 30% 13% 1	2019
October	1st to 10th	Day	25% 4 6% 41% 23% 1	3160
	11th to 20th	Day	38% 4 12% 26% 19% 1	3140
	21st to end	Day	43% 3 12% 30% 11% 1	3253
November	1st to 10th	Day	44% 6% 14% 21% 14% 2	1762
	11th to 20th	Day	55% 5% 12% 19% 9% 1	1644
	21st to end	Day	48% 5% 17% 22% 7% 1	1600
December	1st to 10th	Day	54% 6% 17% 17% 7% 1	2610
	11th to 20th	Day	63% 5% 12% 15% 5%	3005
	21st to end	Day	77% 4 6% 11% 2	3982
January	1st to 10th	Night	57% 4 11% 21% 7%	6348
	11th to 20th	Night	64% 4 9% 12% 11%	6360
	21st to end	Night	56% 4 13% 18% 9%	6609
February	1st to 10th	Night	55% 3 12% 19% 9% 1	2600
	11th to 20th	Night	47% 5% 12% 24% 10% 1	2518
	21st to end	Night	51% 4 12% 21% 12% 1	1980
March	1st to 10th	Night	43% 4 12% 26% 11% 4	5327
	11th to 20th	Night	40% 5% 11% 28% 13% 2	4980
	21st to end	Night	59% 3 10% 16% 10% 1	5203
April	1st to 10th	Night	49% 5% 9% 20% 15% 2	2000
	11th to 20th	Night	48% 5% 10% 19% 16% 2	1975
	21st to end	Night	49% 5% 11% 20% 13% 3	1956
May	1st to 10th	Night	40% 5% 10% 22% 21% 2	3632
	11th to 20th	Night	34% 6% 12% 24% 19% 5%	3597
	21st to end	Night	43% 6% 9% 27% 14% 1	3950
June	1st to 10th	Night	34% 7% 13% 28% 17% 2	1600
	11th to 20th	Night	38% 7% 11% 24% 19% 2	1600
	21st to end	Night	32% 6% 15% 27% 15% 4	1600
July	1st to 10th	Night	37% 6% 17% 25% 13% 2	2530
	11th to 20th	Night	24% 5% 15% 37% 18% 1	2482
	21st to end	Night	29% 8% 16% 24% 20% 2	2662
August	1st to 10th	Night	35% 6% 11% 29% 18% 2	2727
	11th to 20th	Night	32% 5% 13% 31% 17% 1	2873
	21st to end	Night	34% 6% 14% 28% 16% 3	3476
September	1st to 10th	Night	32% 6% 10% 29% 23% 1	1900
	11th to 20th	Night	32% 5% 13% 32% 17% 1	1900
	21st to end	Night	32% 6% 11% 32% 19% 1	2137
October	1st to 10th	Night	25% 3 6% 36% 27% 3	3800
	11th to 20th	Night	32% 4 11% 29% 23% 2	3779
	21st to end	Night	47% 4 9% 26% 14% 1	4294
November	1st to 10th	Night	45% 4 12% 23% 14% 2	2536
	11th to 20th	Night	56% 4 12% 17% 9% 1	2755
	21st to end	Night	53% 4 13% 23% 7% 1	2800
December	1st to 10th	Night	51% 5% 18% 20% 4	4580
	11th to 20th	Night	67% 4 10% 14% 5%	5201
	21st to end	Night	72% 4 8% 12% 4	6996

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	18% 17% 32% 21% 9% 3	300
	11th to 20th	Day	20% 21% 39% 16% 3 1	300
	21st to end	Day	22% 18% 37% 18% 4	330
February	1st to 10th	Day	16% 22% 42% 15% 3 2	300
	11th to 20th	Day	19% 23% 37% 17% 4	300
	21st to end	Day	19% 19% 45% 16% 1	249
March	1st to 10th	Day	22% 18% 41% 13% 5% 1	300
	11th to 20th	Day	24% 15% 39% 15% 6% 2	300
	21st to end	Day	29% 14% 31% 16% 8% 1	438
April	1st to 10th	Day	28% 15% 35% 16% 5%	500
	11th to 20th	Day	30% 16% 28% 17% 9% 1	492
	21st to end	Day	26% 17% 31% 18% 7% 1	540
May	1st to 10th	Day	23% 15% 29% 24% 7% 2	703
	11th to 20th	Day	20% 15% 29% 21% 12% 3	725
	21st to end	Day	21% 11% 26% 24% 14% 4	789
June	1st to 10th	Day	13% 7% 28% 31% 17% 4	730
	11th to 20th	Day	16% 8% 34% 28% 12% 2	730
	21st to end	Day	15% 10% 32% 25% 13% 4	730
July	1st to 10th	Day	10% 4 22% 31% 24% 9%	697
	11th to 20th	Day	8% 7% 28% 31% 19% 7%	668
	21st to end	Day	8% 4 28% 34% 19% 7%	739
August	1st to 10th	Day	8% 5% 23% 33% 23% 8%	676
	11th to 20th	Day	15% 5% 21% 28% 24% 8%	641
	21st to end	Day	11% 6% 26% 28% 22% 7%	539
September	1st to 10th	Day	17% 7% 23% 32% 14% 6%	490
	11th to 20th	Day	11% 7% 30% 31% 16% 5%	490
	21st to end	Day	17% 16% 27% 23% 14% 2	405
October	1st to 10th	Day	18% 13% 29% 27% 10% 3	300
	11th to 20th	Day	26% 17% 34% 15% 7%	300
	21st to end	Day	28% 17% 34% 14% 5% 1	330
November	1st to 10th	Day	20% 14% 38% 22% 6% 1	300
	11th to 20th	Day	23% 19% 38% 16% 4 1	300
	21st to end	Day	23% 18% 40% 14% 5%	300
December	1st to 10th	Day	15% 17% 41% 19% 7%	300
	11th to 20th	Day	23% 19% 33% 18% 6% 1	300
	21st to end	Day	29% 12% 40% 15% 3 1	330
January	1st to 10th	Night	15% 15% 36% 25% 8% 1	1000
	11th to 20th	Night	19% 15% 35% 26% 5% 1	1000
	21st to end	Night	20% 12% 35% 27% 6% 1	1100
February	1st to 10th	Night	16% 15% 35% 28% 5% 1	1000
	11th to 20th	Night	15% 15% 38% 24% 7% 1	963
	21st to end	Night	20% 13% 37% 25% 5%	660
March	1st to 10th	Night	20% 12% 35% 27% 6% 1	780
	11th to 20th	Night	19% 12% 32% 29% 7% 1	600
	21st to end	Night	25% 10% 26% 28% 9% 1	660
April	1st to 10th	Night	23% 12% 36% 23% 5%	600
	11th to 20th	Night	25% 10% 31% 26% 7%	593
	21st to end	Night	24% 9% 30% 28% 8% 1	600
May	1st to 10th	Night	22% 9% 31% 31% 7% 1	600
	11th to 20th	Night	17% 8% 30% 34% 10% 1	591
	21st to end	Night	17% 5% 27% 36% 14% 1	650
June	1st to 10th	Night	13% 5% 28% 41% 13%	600
	11th to 20th	Night	13% 7% 31% 38% 10% 1	600
	21st to end	Night	12% 5% 26% 42% 15% 1	600
July	1st to 10th	Night	8% 1 18% 40% 30% 3	570
	11th to 20th	Night	7% 5% 20% 41% 24% 3	552
	21st to end	Night	5% 2 17% 49% 24% 3	624
August	1st to 10th	Night	7% 2 16% 47% 27% 2	567
	11th to 20th	Night	13% 3 14% 38% 28% 4	564
	21st to end	Night	11% 3 21% 40% 23% 2	627
September	1st to 10th	Night	14% 4 21% 39% 18% 5%	570
	11th to 20th	Night	12% 5% 26% 33% 21% 4	570
	21st to end	Night	15% 9% 26% 34% 15% 2	726
October	1st to 10th	Night	18% 9% 28% 28% 16% 1	760
	11th to 20th	Night	21% 13% 31% 28% 8%	760
	21st to end	Night	23% 11% 29% 29% 7%	836
November	1st to 10th	Night	20% 11% 34% 26% 8% 1	780
	11th to 20th	Night	19% 18% 35% 22% 6%	955
	21st to end	Night	22% 16% 30% 25% 6%	1000
December	1st to 10th	Night	18% 14% 37% 24% 6% 1	1000
	11th to 20th	Night	21% 14% 35% 23% 6%	1000
	21st to end	Night	27% 13% 31% 23% 6%	1100

Page generated at 2025-07-03 00:30:13. Version ac07

Copyright © 2025 Attilla Danko.