Fishcreek Rd Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fishcreek Rd Observing Site clear sky chart from 2005-11-06 to 2025-02-21.

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	16% 11% 4 10% 5% 5% 5% 4 5% 7% 29%	108592
	Night	16% 13% 5% 10% 5% 4 4 3 5% 6% 29%	109973
Transparency	Day	53% 6% 11% 19% 10% 1	112281
	Night	54% 5% 11% 18% 10% 1	114423
Seeing	Day	21% 16% 28% 20% 11% 4	14900
	Night	21% 13% 28% 26% 11% 1	24855

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	14% 21% 7% 26% 5% 4 3 2 2 3 11%	4056
	11th to 20th	Day	12% 22% 8% 19% 8% 7% 4 2 3 3 11%	4060
	21st to end	Day	22% 19% 9% 12% 7% 5% 4 3 3 3 11%	4466
February	1st to 10th	Day	18% 18% 6% 12% 8% 5% 4 2 4 4 20%	1800
	11th to 20th	Day	15% 13% 7% 15% 7% 5% 5% 4 4 5% 19%	1803
	21st to end	Day	18% 16% 4 13% 6% 4 4 3 5% 5% 22%	1570
March	1st to 10th	Day	23% 12% 6% 9% 5% 3 4 3 5% 6% 24%	3366
	11th to 20th	Day	12% 14% 5% 10% 5% 4 4 3 4 6% 32%	3480
	21st to end	Day	22% 11% 5% 9% 4 4 4 3 4 5% 28%	3815
April	1st to 10th	Day	15% 14% 3 7% 5% 6% 4 3 5% 7% 30%	2133
	11th to 20th	Day	18% 12% 3 8% 5% 4 5% 3 5% 6% 32%	2400
	21st to end	Day	20% 11% 3 7% 5% 4 4 3 5% 6% 32%	2470
May	1st to 10th	Day	21% 10% 3 8% 5% 5% 5% 3 6% 6% 29%	4082
	11th to 20th	Day	19% 9% 3 7% 4 5% 4 3 6% 7% 32%	4081
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 4 7% 8% 39%	4539
June	1st to 10th	Day	14% 6% 3 7% 5% 5% 5% 4 7% 8% 36%	2660
	11th to 20th	Day	13% 7% 3 7% 5% 5% 5% 4 6% 8% 37%	2660
	21st to end	Day	12% 5% 2 5% 5% 5% 5% 5% 7% 10% 38%	2654
July	1st to 10th	Day	9% 7% 3 8% 5% 5% 5% 5% 7% 10% 37%	4120
	11th to 20th	Day	10% 5% 2 5% 5% 5% 5% 5% 7% 10% 41%	4120
	21st to end	Day	10% 6% 3 7% 6% 6% 6% 5% 6% 8% 37%	4466
August	1st to 10th	Day	13% 8% 3 7% 5% 5% 6% 4 7% 9% 34%	4104
	11th to 20th	Day	12% 6% 3 7% 5% 5% 6% 5% 8% 9% 34%	4044
	21st to end	Day	9% 6% 2 7% 5% 6% 6% 5% 7% 10% 39%	4445
September	1st to 10th	Day	13% 7% 2 6% 4 5% 4 3 5% 7% 43%	2187
	11th to 20th	Day	10% 6% 2 7% 5% 4 5% 4 5% 8% 43%	2090
	21st to end	Day	20% 9% 3 6% 3 4 4 3 4 7% 37%	2090
October	1st to 10th	Day	15% 7% 2 7% 5% 4 4 4 5% 8% 39%	1957
	11th to 20th	Day	20% 10% 3 8% 4 4 4 4 5% 5% 33%	1900
	21st to end	Day	22% 11% 4 9% 4 4 5% 3 5% 6% 28%	2090
November	1st to 10th	Day	12% 10% 3 8% 5% 4 4 4 5% 7% 38%	1767
	11th to 20th	Day	18% 16% 3 8% 5% 4 4 3 5% 6% 28%	1765
	21st to end	Day	19% 17% 7% 10% 5% 4 5% 4 5% 6% 18%	1600
December	1st to 10th	Day	18% 16% 7% 17% 6% 4 4 3 3 4 17%	2600
	11th to 20th	Day	23% 21% 7% 12% 5% 3 3 3 3 5% 16%	2990
	21st to end	Day	26% 23% 7% 13% 6% 4 3 2 3 4 10%	4162
January	1st to 10th	Night	14% 19% 9% 26% 5% 4 3 2 3 3 11%	5889
	11th to 20th	Night	12% 21% 10% 18% 9% 6% 5% 3 3 3 10%	5900
	21st to end	Night	21% 19% 7% 14% 6% 3 4 2 3 4 16%	6490
February	1st to 10th	Night	20% 16% 5% 12% 7% 4 4 3 5% 4 20%	2600
	11th to 20th	Night	17% 15% 5% 13% 8% 5% 5% 4 4 5% 21%	2480
	21st to end	Night	21% 13% 4 11% 7% 4 4 3 4 4 24%	1885
March	1st to 10th	Night	23% 14% 3 6% 4 3 3 2 3 5% 33%	3485
	11th to 20th	Night	16% 11% 4 8% 5% 4 5% 3 5% 5% 33%	3480
	21st to end	Night	19% 12% 3 7% 5% 4 4 4 4 6% 34%	3817
April	1st to 10th	Night	16% 13% 4 8% 5% 4 4 4 5% 7% 30%	2047
	11th to 20th	Night	17% 10% 3 7% 5% 4 5% 4 6% 6% 33%	1744
	21st to end	Night	15% 9% 3 8% 4 5% 5% 3 6% 7% 36%	1710
May	1st to 10th	Night	25% 10% 3 7% 5% 4 4 4 5% 6% 28%	2813
	11th to 20th	Night	17% 9% 3 6% 4 3 4 4 5% 8% 37%	2812
	21st to end	Night	11% 5% 2 4 3 4 4 4 8% 11% 44%	2998
June	1st to 10th	Night	10% 7% 2 6% 6% 5% 5% 5% 5% 7% 42%	1520
	11th to 20th	Night	11% 6% 1 7% 5% 5% 5% 5% 7% 8% 42%	1520
	21st to end	Night	12% 5% 2 6% 4 5% 4 4 9% 10% 40%	1520
July	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 5% 9% 45%	2839
	11th to 20th	Night	10% 4 2 5% 4 4 4 4 6% 9% 47%	2840
	21st to end	Night	8% 6% 2 6% 4 4 5% 3 7% 9% 45%	3087
August	1st to 10th	Night	11% 8% 3 7% 5% 5% 5% 4 6% 7% 40%	2825
	11th to 20th	Night	15% 9% 2 6% 4 4 4 3 4 6% 44%	2785
	21st to end	Night	8% 5% 2 7% 5% 5% 5% 4 7% 7% 44%	3178
September	1st to 10th	Night	12% 6% 2 6% 4 5% 4 3 5% 8% 46%	1989
	11th to 20th	Night	9% 5% 2 6% 4 3 4 4 5% 8% 51%	2090
	21st to end	Night	16% 7% 3 7% 5% 3 4 3 5% 7% 40%	2090
October	1st to 10th	Night	14% 6% 2 5% 5% 4 4 4 6% 7% 44%	2221
	11th to 20th	Night	19% 7% 3 8% 4 4 4 3 5% 6% 35%	2280
	21st to end	Night	22% 10% 2 7% 4 3 4 4 5% 7% 31%	2508
November	1st to 10th	Night	14% 9% 3 6% 3 5% 4 4 5% 6% 40%	2526
	11th to 20th	Night	17% 16% 4 8% 4 5% 4 3 5% 6% 28%	2631
	21st to end	Night	20% 16% 5% 8% 5% 5% 5% 3 5% 6% 23%	2800
December	1st to 10th	Night	16% 17% 6% 12% 6% 5% 5% 3 4 6% 19%	4580
	11th to 20th	Night	20% 21% 8% 11% 5% 3 3 2 4 4 18%	5205
	21st to end	Night	25% 20% 6% 11% 5% 4 4 3 4 5% 13%	6789

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	80% 3 7% 7% 3	4057
	11th to 20th	Day	80% 3 8% 6% 3	4060
	21st to end	Day	79% 3 6% 8% 3	4466
February	1st to 10th	Day	68% 4 9% 13% 6%	1800
	11th to 20th	Day	67% 5% 8% 13% 6%	1812
	21st to end	Day	63% 5% 11% 13% 6% 1	1570
March	1st to 10th	Day	60% 6% 9% 21% 4	3366
	11th to 20th	Day	53% 6% 13% 22% 6% 1	3480
	21st to end	Day	56% 6% 10% 17% 11% 1	3815
April	1st to 10th	Day	53% 6% 12% 17% 11% 1	2133
	11th to 20th	Day	52% 6% 12% 16% 12% 2	2400
	21st to end	Day	52% 5% 11% 20% 10% 2	2470
May	1st to 10th	Day	53% 6% 10% 21% 9% 1	4120
	11th to 20th	Day	48% 7% 13% 21% 10% 1	4085
	21st to end	Day	39% 8% 14% 20% 15% 5%	4553
June	1st to 10th	Day	44% 7% 13% 23% 12% 1	2660
	11th to 20th	Day	42% 7% 15% 20% 15% 1	2660
	21st to end	Day	39% 8% 13% 23% 16% 1	2654
July	1st to 10th	Day	41% 7% 12% 24% 15% 3	4055
	11th to 20th	Day	36% 6% 13% 25% 19% 1	4051
	21st to end	Day	41% 8% 13% 17% 18% 2	4324
August	1st to 10th	Day	45% 7% 14% 22% 11%	4091
	11th to 20th	Day	42% 7% 12% 28% 10% 1	4083
	21st to end	Day	38% 8% 14% 29% 10% 2	4445
September	1st to 10th	Day	40% 5% 14% 21% 16% 3	2187
	11th to 20th	Day	37% 7% 14% 23% 17% 1	2090
	21st to end	Day	47% 5% 10% 22% 14% 1	2090
October	1st to 10th	Day	34% 5% 13% 28% 19% 1	3256
	11th to 20th	Day	47% 5% 11% 19% 14% 4	3140
	21st to end	Day	43% 4 14% 23% 15% 1	3428
November	1st to 10th	Day	46% 6% 11% 23% 13% 1	1767
	11th to 20th	Day	58% 5% 10% 17% 7% 3	1765
	21st to end	Day	66% 6% 9% 12% 6%	1600
December	1st to 10th	Day	72% 4 11% 10% 2	2600
	11th to 20th	Day	73% 4 8% 12% 2	2986
	21st to end	Day	81% 3 7% 7% 1	4162
January	1st to 10th	Night	78% 4 7% 8% 3	5889
	11th to 20th	Night	80% 4 7% 7% 2	5900
	21st to end	Night	74% 3 9% 9% 5%	6490
February	1st to 10th	Night	67% 5% 9% 14% 5%	2600
	11th to 20th	Night	66% 5% 9% 15% 6%	2482
	21st to end	Night	64% 4 9% 14% 8% 1	1885
March	1st to 10th	Night	55% 4 12% 21% 8%	3485
	11th to 20th	Night	48% 8% 18% 17% 8% 1	3480
	21st to end	Night	50% 6% 9% 23% 10% 1	3817
April	1st to 10th	Night	52% 7% 11% 16% 13% 1	2047
	11th to 20th	Night	48% 7% 11% 17% 14% 3	1744
	21st to end	Night	46% 6% 12% 19% 15% 3	1710
May	1st to 10th	Night	55% 6% 9% 18% 10% 2	2840
	11th to 20th	Night	44% 7% 12% 23% 12% 2	2813
	21st to end	Night	31% 8% 16% 25% 17% 3	3005
June	1st to 10th	Night	40% 7% 10% 25% 15% 3	1520
	11th to 20th	Night	38% 7% 14% 21% 18% 3	1520
	21st to end	Night	36% 8% 13% 25% 16% 2	1520
July	1st to 10th	Night	36% 6% 12% 24% 18% 5%	2794
	11th to 20th	Night	32% 7% 12% 29% 19% 1	2786
	21st to end	Night	35% 7% 14% 18% 24% 2	2988
August	1st to 10th	Night	42% 7% 12% 24% 14% 1	2814
	11th to 20th	Night	42% 5% 10% 29% 12% 1	2812
	21st to end	Night	37% 6% 13% 28% 14% 2	3178
September	1st to 10th	Night	36% 6% 11% 26% 16% 4	1989
	11th to 20th	Night	31% 6% 14% 26% 22% 2	2090
	21st to end	Night	43% 7% 11% 21% 17% 1	2090
October	1st to 10th	Night	32% 5% 10% 29% 23% 1	3702
	11th to 20th	Night	44% 5% 11% 21% 17% 3	3779
	21st to end	Night	40% 4 12% 27% 15% 1	4120
November	1st to 10th	Night	43% 7% 12% 23% 14% 3	2526
	11th to 20th	Night	58% 5% 10% 16% 8% 3	2631
	21st to end	Night	63% 4 12% 16% 5%	2800
December	1st to 10th	Night	67% 6% 11% 12% 3	4580
	11th to 20th	Night	71% 4 10% 13% 2	5208
	21st to end	Night	75% 4 10% 9% 1	6789

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	32% 25% 30% 10% 3	300
	11th to 20th	Day	31% 29% 31% 7% 2	300
	21st to end	Day	28% 34% 28% 7% 2	330
February	1st to 10th	Day	32% 27% 33% 7% 1	300
	11th to 20th	Day	30% 31% 31% 8%	300
	21st to end	Day	32% 32% 31% 5%	225
March	1st to 10th	Day	27% 22% 33% 14% 4	413
	11th to 20th	Day	29% 17% 37% 12% 4 1	460
	21st to end	Day	31% 22% 27% 16% 4	506
April	1st to 10th	Day	23% 26% 28% 16% 6% 1	460
	11th to 20th	Day	29% 19% 26% 15% 7% 3	452
	21st to end	Day	26% 19% 32% 16% 6% 1	460
May	1st to 10th	Day	25% 20% 29% 17% 7% 2	463
	11th to 20th	Day	21% 15% 32% 21% 9% 3	487
	21st to end	Day	15% 10% 29% 23% 18% 5%	529
June	1st to 10th	Day	15% 13% 32% 28% 10% 2	490
	11th to 20th	Day	16% 12% 26% 31% 13% 3	490
	21st to end	Day	14% 10% 34% 24% 13% 4	490
July	1st to 10th	Day	12% 7% 24% 28% 21% 9%	485
	11th to 20th	Day	12% 8% 27% 26% 19% 7%	484
	21st to end	Day	11% 6% 27% 30% 19% 7%	532
August	1st to 10th	Day	14% 7% 23% 27% 22% 7%	486
	11th to 20th	Day	15% 9% 24% 27% 16% 9%	479
	21st to end	Day	10% 6% 23% 28% 22% 10%	539
September	1st to 10th	Day	14% 9% 23% 26% 20% 8%	490
	11th to 20th	Day	9% 5% 20% 30% 26% 9%	490
	21st to end	Day	25% 11% 24% 21% 14% 5%	490
October	1st to 10th	Day	14% 11% 32% 21% 19% 3	490
	11th to 20th	Day	23% 19% 32% 16% 8% 2	490
	21st to end	Day	30% 19% 28% 19% 4	539
November	1st to 10th	Day	19% 25% 33% 13% 10% 1	305
	11th to 20th	Day	30% 26% 27% 13% 3 1	283
	21st to end	Day	25% 28% 37% 10% 1	200
December	1st to 10th	Day	27% 25% 33% 11% 3 2	200
	11th to 20th	Day	29% 28% 32% 11% 2	200
	21st to end	Day	33% 27% 28% 11% 1	263
January	1st to 10th	Night	26% 23% 34% 14% 4	800
	11th to 20th	Night	30% 24% 29% 14% 3	800
	21st to end	Night	28% 21% 30% 19% 3	880
February	1st to 10th	Night	29% 20% 30% 20% 2	800
	11th to 20th	Night	27% 20% 33% 18% 2	783
	21st to end	Night	28% 21% 33% 15% 2	629
March	1st to 10th	Night	22% 18% 35% 21% 4	760
	11th to 20th	Night	23% 18% 31% 22% 6% 1	760
	21st to end	Night	24% 14% 32% 22% 7%	836
April	1st to 10th	Night	23% 16% 33% 23% 6%	760
	11th to 20th	Night	22% 14% 35% 20% 9%	620
	21st to end	Night	17% 14% 35% 28% 6%	570
May	1st to 10th	Night	21% 11% 28% 31% 8% 1	570
	11th to 20th	Night	18% 8% 27% 35% 10% 2	561
	21st to end	Night	13% 4 25% 37% 19% 2	574
June	1st to 10th	Night	11% 4 32% 38% 13% 1	380
	11th to 20th	Night	12% 5% 25% 43% 13% 1	380
	21st to end	Night	12% 6% 27% 37% 17%	380
July	1st to 10th	Night	9% 4 16% 40% 27% 3	554
	11th to 20th	Night	9% 4 21% 39% 24% 4	552
	21st to end	Night	9% 4 16% 43% 26% 2	624
August	1st to 10th	Night	9% 3 16% 42% 26% 3	567
	11th to 20th	Night	12% 3 17% 38% 29% 3	564
	21st to end	Night	11% 2 20% 35% 29% 4	655
September	1st to 10th	Night	14% 6% 18% 34% 24% 4	760
	11th to 20th	Night	11% 3 17% 37% 27% 4	760
	21st to end	Night	18% 9% 23% 29% 17% 4	760
October	1st to 10th	Night	17% 8% 27% 27% 19% 2	760
	11th to 20th	Night	23% 13% 29% 25% 9% 1	760
	21st to end	Night	27% 15% 29% 24% 5%	836
November	1st to 10th	Night	19% 14% 30% 26% 10%	780
	11th to 20th	Night	26% 19% 31% 18% 6% 1	800
	21st to end	Night	30% 18% 31% 15% 6%	800
December	1st to 10th	Night	31% 18% 31% 16% 4	800
	11th to 20th	Night	27% 22% 32% 17% 2	800
	21st to end	Night	30% 17% 34% 17% 2	880

Page generated at 2025-02-18 03:26:29. Version ac07

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