Dave's Falls County Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dave's Falls County Park clear sky chart from 2005-11-06 to 2024-01-12.

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	14% 8% 3 7% 6% 3 5% 5% 6% 7% 35%	74785
	Night	14% 9% 4 7% 5% 3 5% 4 5% 7% 37%	74954
Transparency	Day	46% 8% 13% 21% 11% 1	74486
	Night	46% 7% 13% 22% 11% 1	74774
Seeing	Day	18% 15% 32% 22% 10% 3	14836
	Night	18% 10% 34% 28% 10% 1	24851

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% 4 8% 6% 4 6% 5% 7% 6% 31%	1517
	11th to 20th	Day	14% 13% 7% 11% 8% 4 5% 4 5% 6% 24%	1448
	21st to end	Day	13% 14% 6% 10% 6% 4 5% 4 5% 6% 27%	1584
February	1st to 10th	Day	9% 11% 4 9% 6% 4 5% 3 6% 8% 35%	1547
	11th to 20th	Day	11% 12% 4 8% 6% 3 5% 5% 4 6% 37%	1699
	21st to end	Day	14% 13% 5% 8% 6% 2 4 4 5% 6% 33%	1480
March	1st to 10th	Day	11% 11% 4 6% 7% 3 6% 4 5% 7% 35%	1800
	11th to 20th	Day	11% 11% 4 8% 5% 3 4 4 4 6% 38%	1850
	21st to end	Day	18% 11% 4 8% 7% 4 5% 4 4 5% 30%	2376
April	1st to 10th	Day	16% 13% 4 7% 7% 3 5% 6% 5% 6% 29%	2160
	11th to 20th	Day	21% 10% 3 6% 5% 3 5% 4 5% 6% 32%	2134
	21st to end	Day	19% 9% 3 6% 5% 4 5% 4 5% 7% 33%	2335
May	1st to 10th	Day	16% 7% 4 7% 7% 4 5% 5% 5% 6% 34%	2420
	11th to 20th	Day	15% 6% 3 7% 6% 3 5% 5% 5% 6% 38%	2479
	21st to end	Day	12% 6% 3 6% 6% 3 6% 5% 6% 9% 38%	2725
June	1st to 10th	Day	11% 5% 3 5% 6% 3 5% 5% 6% 9% 43%	2520
	11th to 20th	Day	14% 5% 2 6% 6% 4 5% 5% 6% 8% 39%	2520
	21st to end	Day	13% 6% 2 5% 6% 3 6% 6% 6% 9% 39%	2520
July	1st to 10th	Day	7% 4 2 4 5% 3 6% 5% 6% 11% 45%	2520
	11th to 20th	Day	8% 5% 2 5% 5% 4 6% 6% 6% 9% 44%	2520
	21st to end	Day	8% 4 2 5% 6% 4 5% 6% 6% 9% 45%	2743
August	1st to 10th	Day	9% 4 3 6% 6% 3 6% 6% 7% 10% 40%	2507
	11th to 20th	Day	11% 5% 3 6% 6% 3 5% 5% 5% 8% 42%	2306
	21st to end	Day	13% 5% 2 5% 5% 3 5% 5% 6% 8% 43%	2376
September	1st to 10th	Day	13% 6% 2 6% 6% 3 4 5% 5% 7% 43%	2160
	11th to 20th	Day	11% 5% 2 5% 5% 4 5% 6% 7% 9% 41%	2057
	21st to end	Day	12% 6% 3 7% 6% 4 6% 6% 7% 8% 34%	1980
October	1st to 10th	Day	17% 6% 3 7% 5% 3 4 6% 6% 7% 37%	1900
	11th to 20th	Day	21% 10% 4 7% 7% 5% 4 4 6% 8% 27%	1730
	21st to end	Day	21% 10% 4 7% 6% 3 5% 4 4 6% 30%	1782
November	1st to 10th	Day	13% 9% 3 8% 5% 3 5% 5% 4 7% 38%	1672
	11th to 20th	Day	15% 10% 6% 7% 7% 4 6% 5% 6% 7% 27%	1677
	21st to end	Day	15% 12% 4 6% 6% 3 5% 5% 7% 8% 29%	1520
December	1st to 10th	Day	11% 12% 5% 8% 7% 4 5% 4 6% 6% 32%	1520
	11th to 20th	Day	16% 13% 5% 8% 6% 4 6% 5% 5% 6% 26%	1918
	21st to end	Day	22% 21% 6% 9% 5% 3 3 3 4 4 19%	2783
January	1st to 10th	Night	12% 11% 6% 8% 7% 4 6% 4 5% 6% 33%	2648
	11th to 20th	Night	15% 13% 6% 9% 8% 4 5% 4 4 5% 27%	2541
	21st to end	Night	11% 13% 6% 10% 7% 4 6% 5% 5% 7% 26%	2772
February	1st to 10th	Night	10% 12% 6% 9% 7% 4 4 4 5% 6% 33%	2412
	11th to 20th	Night	11% 10% 4 8% 7% 3 6% 4 6% 7% 35%	2146
	21st to end	Night	15% 13% 5% 7% 6% 3 4 4 5% 5% 32%	1776
March	1st to 10th	Night	12% 9% 4 7% 5% 3 5% 5% 4 6% 40%	2160
	11th to 20th	Night	13% 7% 4 6% 5% 3 5% 5% 5% 6% 42%	2126
	21st to end	Night	16% 8% 4 7% 6% 3 6% 4 5% 6% 37%	1980
April	1st to 10th	Night	19% 9% 4 8% 6% 3 5% 4 5% 8% 30%	1800
	11th to 20th	Night	22% 7% 3 6% 4 2 4 4 5% 6% 37%	1775
	21st to end	Night	16% 8% 3 6% 6% 4 5% 4 5% 8% 35%	1623
May	1st to 10th	Night	18% 7% 3 7% 5% 3 6% 5% 6% 7% 32%	1535
	11th to 20th	Night	16% 9% 3 6% 6% 3 4 3 5% 6% 39%	1416
	21st to end	Night	12% 5% 3 5% 4 3 5% 5% 6% 9% 44%	1551
June	1st to 10th	Night	11% 4 3 5% 5% 4 5% 5% 5% 8% 46%	1440
	11th to 20th	Night	13% 7% 3 7% 5% 3 5% 5% 6% 7% 39%	1440
	21st to end	Night	12% 5% 2 5% 4 2 4 5% 7% 9% 44%	1440
July	1st to 10th	Night	7% 3 1 4 3 3 4 5% 6% 9% 54%	1440
	11th to 20th	Night	10% 3 2 5% 4 3 4 4 5% 9% 50%	1440
	21st to end	Night	7% 4 3 4 4 2 3 5% 6% 8% 53%	1575
August	1st to 10th	Night	8% 5% 2 5% 5% 4 4 4 7% 8% 48%	1432
	11th to 20th	Night	8% 4 2 5% 5% 3 5% 4 5% 8% 50%	1591
	21st to end	Night	12% 6% 2 4 5% 3 3 3 4 7% 51%	1980
September	1st to 10th	Night	10% 5% 2 5% 4 3 3 5% 5% 7% 52%	1800
	11th to 20th	Night	12% 4 2 4 4 3 4 5% 4 7% 51%	1885
	21st to end	Night	15% 6% 2 6% 4 2 3 4 5% 9% 42%	1980
October	1st to 10th	Night	15% 6% 2 4 5% 2 5% 4 5% 7% 44%	2057
	11th to 20th	Night	17% 10% 3 7% 6% 3 4 5% 5% 7% 33%	2229
	21st to end	Night	20% 10% 4 5% 6% 3 4 4 5% 7% 32%	2574
November	1st to 10th	Night	15% 8% 3 6% 5% 3 5% 4 5% 7% 39%	2406
	11th to 20th	Night	15% 10% 3 8% 6% 3 5% 4 5% 7% 33%	2501
	21st to end	Night	15% 11% 4 7% 6% 4 5% 5% 4 7% 32%	2660
December	1st to 10th	Night	13% 13% 5% 7% 6% 3 4 4 5% 6% 32%	2660
	11th to 20th	Night	13% 13% 6% 8% 7% 4 5% 5% 4 5% 30%	3279
	21st to end	Night	25% 19% 7% 7% 5% 3 3 3 4 4 22%	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	52% 7% 12% 19% 9% 1	1518
	11th to 20th	Day	60% 7% 11% 14% 7% 1	1448
	21st to end	Day	56% 6% 14% 15% 7% 1	1584
February	1st to 10th	Day	48% 6% 14% 19% 12% 1	1547
	11th to 20th	Day	48% 6% 13% 23% 9% 1	1709
	21st to end	Day	52% 6% 11% 18% 11% 1	1480
March	1st to 10th	Day	49% 7% 12% 18% 13% 2	1800
	11th to 20th	Day	48% 6% 11% 22% 10% 3	1850
	21st to end	Day	56% 6% 11% 16% 10% 1	2376
April	1st to 10th	Day	55% 6% 12% 17% 9% 1	2160
	11th to 20th	Day	53% 6% 9% 19% 11% 1	2134
	21st to end	Day	51% 6% 9% 17% 13% 2	2335
May	1st to 10th	Day	49% 7% 13% 19% 10% 2	2420
	11th to 20th	Day	45% 7% 11% 21% 14% 1	2483
	21st to end	Day	42% 9% 13% 23% 12% 2	2725
June	1st to 10th	Day	36% 8% 14% 25% 14% 2	2520
	11th to 20th	Day	43% 8% 14% 19% 15% 1	2520
	21st to end	Day	40% 9% 15% 23% 12% 1	2520
July	1st to 10th	Day	30% 9% 15% 28% 16% 1	2451
	11th to 20th	Day	34% 9% 14% 25% 15% 3	2445
	21st to end	Day	33% 9% 16% 24% 17% 1	2591
August	1st to 10th	Day	36% 11% 15% 24% 12% 2	2492
	11th to 20th	Day	38% 8% 15% 25% 13% 1	2306
	21st to end	Day	37% 9% 15% 23% 15% 1	2376
September	1st to 10th	Day	40% 8% 12% 26% 13% 1	2160
	11th to 20th	Day	38% 10% 19% 26% 7%	2057
	21st to end	Day	44% 9% 14% 26% 7%	1980
October	1st to 10th	Day	44% 9% 13% 25% 8%	1900
	11th to 20th	Day	55% 6% 13% 19% 6% 1	1730
	21st to end	Day	56% 7% 11% 18% 7%	1782
November	1st to 10th	Day	45% 6% 13% 24% 11%	1672
	11th to 20th	Day	54% 8% 14% 16% 8%	1677
	21st to end	Day	51% 9% 16% 18% 4 1	1520
December	1st to 10th	Day	51% 8% 13% 22% 6%	1520
	11th to 20th	Day	57% 8% 12% 15% 7% 1	1915
	21st to end	Day	69% 6% 7% 13% 5%	2783
January	1st to 10th	Night	52% 6% 13% 18% 9% 1	2648
	11th to 20th	Night	59% 7% 11% 17% 6%	2541
	21st to end	Night	56% 7% 10% 17% 9% 1	2772
February	1st to 10th	Night	52% 4 11% 20% 11% 2	2412
	11th to 20th	Night	47% 7% 12% 21% 10% 3	2147
	21st to end	Night	54% 5% 13% 19% 9% 1	1776
March	1st to 10th	Night	45% 6% 14% 23% 11% 2	2160
	11th to 20th	Night	43% 6% 13% 23% 13% 1	2126
	21st to end	Night	48% 6% 11% 20% 13% 2	1980
April	1st to 10th	Night	53% 6% 11% 15% 14% 1	1800
	11th to 20th	Night	48% 5% 10% 22% 12% 3	1775
	21st to end	Night	48% 7% 11% 19% 13% 2	1623
May	1st to 10th	Night	48% 7% 13% 20% 10% 2	1535
	11th to 20th	Night	47% 7% 10% 22% 12% 2	1417
	21st to end	Night	36% 8% 18% 22% 14% 2	1552
June	1st to 10th	Night	35% 8% 13% 28% 15% 2	1440
	11th to 20th	Night	42% 7% 12% 23% 15% 2	1440
	21st to end	Night	34% 8% 17% 28% 12% 2	1440
July	1st to 10th	Night	25% 8% 14% 31% 21% 1	1400
	11th to 20th	Night	30% 7% 18% 27% 14% 4	1392
	21st to end	Night	26% 9% 17% 29% 17% 2	1487
August	1st to 10th	Night	33% 9% 14% 27% 14% 2	1423
	11th to 20th	Night	31% 9% 14% 28% 15% 2	1591
	21st to end	Night	35% 6% 14% 26% 18% 2	1980
September	1st to 10th	Night	32% 8% 13% 31% 16%	1800
	11th to 20th	Night	32% 8% 16% 34% 10%	1885
	21st to end	Night	40% 7% 17% 28% 8% 1	1980
October	1st to 10th	Night	38% 9% 13% 29% 10% 1	2057
	11th to 20th	Night	49% 7% 14% 21% 8% 1	2229
	21st to end	Night	51% 6% 14% 20% 8%	2574
November	1st to 10th	Night	45% 6% 13% 23% 13%	2406
	11th to 20th	Night	50% 7% 14% 19% 10%	2501
	21st to end	Night	51% 7% 15% 21% 5% 1	2660
December	1st to 10th	Night	52% 7% 14% 20% 7%	2660
	11th to 20th	Night	55% 7% 12% 19% 7%	3281
	21st to end	Night	66% 6% 8% 15% 5%	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	19% 15% 35% 22% 8% 1	270
	11th to 20th	Day	25% 16% 33% 21% 4 1	243
	21st to end	Day	23% 12% 42% 19% 5%	264
February	1st to 10th	Day	15% 25% 41% 15% 3	240
	11th to 20th	Day	20% 27% 35% 14% 5%	240
	21st to end	Day	27% 21% 42% 9% 1	198
March	1st to 10th	Day	17% 26% 41% 12% 3	240
	11th to 20th	Day	20% 19% 36% 18% 7%	266
	21st to end	Day	27% 18% 26% 20% 8%	462
April	1st to 10th	Day	25% 18% 31% 19% 6% 1	420
	11th to 20th	Day	27% 19% 26% 18% 8% 1	412
	21st to end	Day	25% 15% 28% 21% 9% 2	420
May	1st to 10th	Day	22% 20% 30% 17% 8% 2	503
	11th to 20th	Day	18% 18% 34% 20% 7% 3	625
	21st to end	Day	16% 15% 30% 25% 8% 5%	679
June	1st to 10th	Day	10% 17% 35% 25% 10% 3	630
	11th to 20th	Day	17% 12% 36% 23% 10% 2	630
	21st to end	Day	15% 11% 32% 28% 10% 4	630
July	1st to 10th	Day	8% 9% 31% 33% 15% 5%	621
	11th to 20th	Day	10% 11% 34% 27% 13% 6%	618
	21st to end	Day	7% 9% 35% 28% 14% 7%	684
August	1st to 10th	Day	9% 8% 31% 29% 18% 5%	626
	11th to 20th	Day	12% 9% 23% 28% 19% 8%	486
	21st to end	Day	16% 10% 24% 24% 20% 6%	495
September	1st to 10th	Day	16% 11% 26% 27% 15% 6%	450
	11th to 20th	Day	13% 8% 29% 32% 16% 3	450
	21st to end	Day	19% 15% 25% 24% 14% 3	450
October	1st to 10th	Day	23% 15% 28% 19% 13% 2	370
	11th to 20th	Day	24% 23% 33% 16% 3	270
	21st to end	Day	30% 20% 33% 13% 3	297
November	1st to 10th	Day	17% 20% 36% 19% 7% 1	270
	11th to 20th	Day	20% 25% 33% 15% 5% 1	270
	21st to end	Day	21% 21% 39% 13% 6%	270
December	1st to 10th	Day	18% 18% 39% 19% 5% 1	270
	11th to 20th	Day	24% 21% 37% 13% 4	270
	21st to end	Day	29% 20% 33% 14% 3	297
January	1st to 10th	Night	17% 12% 42% 24% 5%	950
	11th to 20th	Night	20% 13% 37% 23% 7% 1	908
	21st to end	Night	19% 9% 40% 23% 7% 1	990
February	1st to 10th	Night	16% 13% 41% 25% 5%	900
	11th to 20th	Night	18% 16% 37% 23% 6%	751
	21st to end	Night	22% 14% 38% 23% 3	592
March	1st to 10th	Night	16% 12% 36% 28% 7%	720
	11th to 20th	Night	16% 15% 42% 21% 6%	712
	21st to end	Night	18% 10% 34% 29% 8% 1	594
April	1st to 10th	Night	21% 14% 34% 25% 6%	540
	11th to 20th	Night	26% 8% 30% 29% 6%	533
	21st to end	Night	20% 10% 32% 29% 9%	540
May	1st to 10th	Night	23% 10% 30% 29% 7% 1	540
	11th to 20th	Night	20% 11% 33% 29% 6% 1	531
	21st to end	Night	15% 7% 30% 35% 13%	584
June	1st to 10th	Night	13% 7% 29% 40% 11%	540
	11th to 20th	Night	17% 7% 28% 37% 10% 1	540
	21st to end	Night	14% 6% 26% 40% 14% 1	540
July	1st to 10th	Night	7% 4 24% 45% 20% 1	525
	11th to 20th	Night	9% 4 30% 39% 18%	522
	21st to end	Night	9% 4 30% 37% 19% 2	591
August	1st to 10th	Night	10% 3 25% 40% 20% 2	537
	11th to 20th	Night	9% 3 22% 38% 25% 3	534
	21st to end	Night	13% 6% 24% 38% 19% 1	594
September	1st to 10th	Night	11% 6% 26% 32% 21% 3	540
	11th to 20th	Night	13% 5% 31% 31% 17% 2	625
	21st to end	Night	18% 9% 29% 28% 15% 1	720
October	1st to 10th	Night	18% 10% 30% 27% 14% 1	720
	11th to 20th	Night	21% 13% 34% 24% 8%	720
	21st to end	Night	26% 10% 33% 24% 7% 1	792
November	1st to 10th	Night	20% 11% 37% 26% 6% 1	740
	11th to 20th	Night	20% 16% 37% 21% 6%	791
	21st to end	Night	21% 14% 34% 26% 5%	950
December	1st to 10th	Night	21% 14% 39% 21% 6% 1	950
	11th to 20th	Night	20% 13% 36% 24% 6% 1	950
	21st to end	Night	27% 11% 37% 21% 3	1045

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