Pioneer Scout Reservation
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pioneer Scout Reservation clear sky chart from 2005-11-06 to 2024-04-25.

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% 10% 4 7% 6% 3 5% 5% 6% 7% 32%	83279
	Night	15% 10% 4 7% 6% 3 4 5% 5% 7% 34%	85869
Transparency	Day	50% 6% 12% 20% 11% 1	82987
	Night	50% 6% 12% 20% 12% 1	85682
Seeing	Day	17% 9% 27% 25% 15% 7%	14856
	Night	19% 8% 29% 30% 13% 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	16% 17% 8% 11% 8% 4 5% 5% 5% 5% 19%	2527
	11th to 20th	Day	15% 16% 8% 12% 8% 4 6% 8% 6% 5% 13%	2530
	21st to end	Day	24% 19% 10% 13% 7% 3 3 2 2 4 14%	2951
February	1st to 10th	Day	14% 15% 5% 10% 10% 4 5% 5% 4 7% 21%	1752
	11th to 20th	Day	15% 10% 5% 11% 9% 4 5% 5% 6% 6% 25%	1848
	21st to end	Day	16% 12% 6% 11% 7% 3 4 4 6% 7% 26%	1570
March	1st to 10th	Day	18% 14% 5% 8% 8% 4 4 5% 4 6% 25%	3120
	11th to 20th	Day	12% 8% 3 9% 7% 4 6% 6% 6% 8% 32%	3468
	21st to end	Day	20% 11% 6% 8% 6% 4 5% 4 4 6% 25%	3832
April	1st to 10th	Day	17% 10% 4 6% 6% 4 5% 6% 6% 7% 29%	2280
	11th to 20th	Day	17% 8% 3 6% 5% 3 5% 4 5% 6% 36%	2335
	21st to end	Day	17% 9% 3 7% 5% 3 5% 4 5% 8% 34%	2394
May	1st to 10th	Day	17% 8% 4 6% 7% 3 6% 6% 5% 7% 31%	2340
	11th to 20th	Day	19% 8% 3 6% 5% 3 5% 4 6% 7% 34%	2301
	21st to end	Day	10% 6% 3 6% 5% 4 6% 5% 6% 10% 39%	2575
June	1st to 10th	Day	10% 6% 2 6% 5% 4 6% 6% 6% 8% 41%	2520
	11th to 20th	Day	9% 6% 2 5% 5% 4 6% 5% 6% 9% 43%	2520
	21st to end	Day	11% 4 2 6% 6% 3 6% 7% 7% 10% 38%	2520
July	1st to 10th	Day	7% 5% 2 5% 5% 3 4 6% 7% 10% 45%	2520
	11th to 20th	Day	8% 4 3 4 5% 4 5% 6% 7% 10% 44%	2520
	21st to end	Day	7% 4 3 5% 6% 4 6% 6% 6% 9% 44%	2645
August	1st to 10th	Day	6% 4 2 5% 6% 3 6% 6% 8% 9% 44%	2327
	11th to 20th	Day	10% 5% 2 5% 5% 4 6% 6% 6% 10% 40%	2303
	21st to end	Day	9% 5% 2 5% 5% 3 5% 5% 6% 10% 45%	2444
September	1st to 10th	Day	12% 6% 3 5% 6% 3 4 5% 6% 8% 42%	2081
	11th to 20th	Day	11% 4 2 4 4 3 5% 6% 7% 10% 44%	1980
	21st to end	Day	12% 7% 2 5% 5% 3 5% 4 6% 8% 42%	1980
October	1st to 10th	Day	13% 6% 3 6% 6% 3 4 5% 5% 7% 43%	1980
	11th to 20th	Day	17% 7% 3 7% 5% 4 5% 5% 6% 7% 34%	1807
	21st to end	Day	19% 11% 3 7% 6% 3 5% 4 6% 7% 28%	1782
November	1st to 10th	Day	12% 8% 3 6% 5% 2 3 4 6% 7% 43%	1672
	11th to 20th	Day	16% 13% 4 7% 7% 3 4 4 4 6% 30%	1710
	21st to end	Day	20% 14% 5% 8% 6% 3 5% 4 5% 5% 25%	1710
December	1st to 10th	Day	15% 15% 7% 12% 8% 3 4 4 5% 5% 22%	1710
	11th to 20th	Day	15% 14% 6% 11% 7% 3 6% 5% 5% 6% 22%	1942
	21st to end	Day	22% 21% 10% 10% 7% 3 4 4 4 5% 11%	2783
January	1st to 10th	Night	16% 14% 7% 10% 7% 4 4 5% 4 6% 21%	4428
	11th to 20th	Night	15% 16% 8% 13% 8% 4 4 7% 5% 5% 14%	4440
	21st to end	Night	24% 17% 7% 10% 7% 3 4 4 4 5% 14%	4695
February	1st to 10th	Night	17% 13% 5% 8% 8% 4 5% 4 5% 6% 24%	2428
	11th to 20th	Night	14% 11% 5% 8% 7% 4 6% 5% 5% 6% 28%	2218
	21st to end	Night	20% 11% 4 7% 6% 3 5% 5% 4 5% 30%	1884
March	1st to 10th	Night	17% 12% 4 7% 5% 3 4 3 5% 6% 35%	3733
	11th to 20th	Night	9% 7% 3 5% 6% 4 5% 5% 6% 8% 44%	3490
	21st to end	Night	17% 9% 4 8% 6% 3 4 4 5% 6% 34%	3817
April	1st to 10th	Night	15% 8% 3 6% 5% 3 3 5% 6% 8% 37%	1910
	11th to 20th	Night	19% 7% 3 5% 6% 3 4 4 5% 6% 38%	1792
	21st to end	Night	18% 8% 3 5% 5% 2 4 5% 5% 7% 38%	1665
May	1st to 10th	Night	17% 8% 4 7% 7% 4 5% 5% 6% 8% 30%	1620
	11th to 20th	Night	21% 7% 2 5% 5% 3 4 4 4 7% 38%	1592
	21st to end	Night	11% 4 3 5% 5% 4 4 6% 7% 10% 43%	1696
June	1st to 10th	Night	10% 4 2 4 5% 3 4 5% 6% 9% 48%	1440
	11th to 20th	Night	8% 5% 3 6% 6% 3 5% 5% 6% 7% 45%	1440
	21st to end	Night	8% 4 2 5% 6% 3 4 5% 7% 9% 46%	1440
July	1st to 10th	Night	6% 5% 2 4 4 3 4 4 6% 8% 53%	1440
	11th to 20th	Night	8% 4 2 5% 4 2 4 4 4 8% 55%	1440
	21st to end	Night	5% 4 2 4 5% 3 5% 5% 7% 10% 50%	1670
August	1st to 10th	Night	6% 3 2 4 4 3 4 6% 6% 10% 51%	1611
	11th to 20th	Night	7% 5% 1 4 5% 3 5% 5% 6% 8% 50%	1598
	21st to end	Night	9% 3 2 4 5% 4 5% 5% 5% 9% 51%	1908
September	1st to 10th	Night	10% 6% 2 5% 4 3 4 4 5% 6% 50%	1860
	11th to 20th	Night	9% 4 2 3 5% 2 4 4 5% 7% 55%	1980
	21st to end	Night	13% 6% 2 6% 4 3 4 5% 4 6% 47%	1980
October	1st to 10th	Night	12% 7% 3 5% 4 3 3 4 5% 8% 47%	1980
	11th to 20th	Night	17% 8% 4 6% 6% 3 4 5% 5% 6% 36%	2150
	21st to end	Night	20% 9% 3 6% 5% 3 4 4 5% 6% 36%	2574
November	1st to 10th	Night	12% 8% 3 6% 6% 4 4 4 5% 7% 42%	2406
	11th to 20th	Night	17% 10% 3 8% 6% 3 5% 4 5% 7% 32%	2470
	21st to end	Night	18% 12% 6% 7% 6% 4 4 5% 4 6% 29%	2470
December	1st to 10th	Night	18% 12% 6% 11% 7% 4 5% 5% 6% 6% 21%	2470
	11th to 20th	Night	17% 13% 6% 10% 8% 4 5% 4 5% 6% 23%	3250
	21st to end	Night	26% 17% 7% 10% 6% 3 4 4 4 5% 13%	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	67% 6% 10% 12% 5%	2528
	11th to 20th	Day	69% 5% 12% 9% 6%	2530
	21st to end	Day	77% 4 7% 9% 3	2951
February	1st to 10th	Day	64% 5% 10% 13% 7% 1	1752
	11th to 20th	Day	59% 5% 10% 16% 9% 1	1858
	21st to end	Day	57% 5% 13% 16% 6% 2	1570
March	1st to 10th	Day	61% 5% 9% 18% 6%	3120
	11th to 20th	Day	46% 6% 16% 22% 9% 1	3468
	21st to end	Day	59% 6% 11% 17% 6% 1	3832
April	1st to 10th	Day	52% 6% 11% 19% 11%	2280
	11th to 20th	Day	48% 6% 11% 22% 12% 2	2335
	21st to end	Day	49% 5% 13% 18% 13% 2	2394
May	1st to 10th	Day	51% 7% 13% 19% 10%	2340
	11th to 20th	Day	49% 6% 11% 19% 14% 2	2305
	21st to end	Day	40% 7% 13% 25% 13% 2	2575
June	1st to 10th	Day	39% 7% 11% 26% 15% 2	2520
	11th to 20th	Day	36% 7% 13% 24% 18% 2	2520
	21st to end	Day	40% 8% 13% 22% 15% 3	2520
July	1st to 10th	Day	32% 8% 14% 24% 18% 4	2451
	11th to 20th	Day	33% 8% 13% 27% 17% 2	2445
	21st to end	Day	34% 8% 14% 24% 18% 2	2498
August	1st to 10th	Day	33% 9% 16% 26% 15% 1	2314
	11th to 20th	Day	37% 10% 12% 26% 14% 1	2303
	21st to end	Day	35% 6% 11% 26% 17% 4	2444
September	1st to 10th	Day	40% 7% 14% 21% 16% 2	2081
	11th to 20th	Day	33% 7% 12% 28% 19% 1	1980
	21st to end	Day	38% 5% 13% 25% 18% 1	1980
October	1st to 10th	Day	41% 5% 12% 25% 16% 2	1980
	11th to 20th	Day	47% 6% 10% 22% 14%	1807
	21st to end	Day	54% 5% 14% 17% 8% 1	1782
November	1st to 10th	Day	40% 5% 13% 26% 16% 1	1672
	11th to 20th	Day	55% 5% 11% 18% 10% 1	1710
	21st to end	Day	60% 4 12% 16% 7%	1710
December	1st to 10th	Day	66% 5% 11% 12% 5%	1710
	11th to 20th	Day	60% 7% 13% 15% 5%	1939
	21st to end	Day	77% 5% 7% 6% 5%	2783
January	1st to 10th	Night	62% 6% 10% 15% 6%	4428
	11th to 20th	Night	70% 4 12% 10% 4	4440
	21st to end	Night	73% 5% 9% 9% 3	4695
February	1st to 10th	Night	60% 5% 11% 16% 6% 1	2428
	11th to 20th	Night	55% 5% 8% 21% 9% 1	2219
	21st to end	Night	56% 5% 10% 18% 9% 2	1884
March	1st to 10th	Night	51% 5% 11% 24% 9% 1	3733
	11th to 20th	Night	36% 6% 15% 23% 18% 2	3490
	21st to end	Night	50% 5% 13% 22% 8% 1	3817
April	1st to 10th	Night	45% 6% 10% 23% 14% 2	1910
	11th to 20th	Night	47% 5% 10% 19% 18% 2	1792
	21st to end	Night	46% 5% 11% 20% 16% 3	1665
May	1st to 10th	Night	51% 7% 11% 18% 10% 2	1620
	11th to 20th	Night	46% 6% 9% 20% 17% 2	1593
	21st to end	Night	37% 6% 16% 26% 13% 2	1697
June	1st to 10th	Night	33% 5% 13% 27% 19% 3	1440
	11th to 20th	Night	36% 8% 13% 24% 18% 2	1440
	21st to end	Night	31% 8% 16% 25% 17% 2	1440
July	1st to 10th	Night	30% 7% 14% 23% 23% 4	1400
	11th to 20th	Night	29% 6% 16% 25% 21% 3	1392
	21st to end	Night	27% 7% 15% 25% 20% 5%	1577
August	1st to 10th	Night	27% 7% 15% 31% 18% 2	1600
	11th to 20th	Night	30% 7% 16% 27% 17% 3	1598
	21st to end	Night	31% 6% 12% 25% 23% 4	1908
September	1st to 10th	Night	34% 6% 11% 27% 19% 4	1860
	11th to 20th	Night	29% 6% 9% 30% 24% 1	1980
	21st to end	Night	38% 6% 10% 28% 17% 2	1980
October	1st to 10th	Night	36% 6% 10% 28% 19% 1	1980
	11th to 20th	Night	47% 6% 10% 20% 16% 1	2150
	21st to end	Night	49% 5% 10% 23% 12% 1	2574
November	1st to 10th	Night	41% 6% 11% 24% 16% 1	2406
	11th to 20th	Night	51% 4 12% 21% 10% 2	2470
	21st to end	Night	56% 5% 12% 20% 7%	2470
December	1st to 10th	Night	61% 6% 11% 15% 7%	2470
	11th to 20th	Night	62% 4 13% 13% 7% 1	3252
	21st to end	Night	73% 5% 11% 8% 3	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	25% 16% 31% 21% 6% 1	270
	11th to 20th	Day	23% 13% 45% 15% 4 1	270
	21st to end	Day	27% 13% 30% 23% 7% 1	297
February	1st to 10th	Day	23% 15% 31% 24% 4 2	270
	11th to 20th	Day	23% 15% 37% 20% 4	270
	21st to end	Day	24% 17% 39% 17% 3	225
March	1st to 10th	Day	20% 17% 40% 18% 4	270
	11th to 20th	Day	21% 12% 35% 24% 7% 2	448
	21st to end	Day	31% 11% 31% 19% 7% 1	506
April	1st to 10th	Day	20% 15% 33% 22% 11%	460
	11th to 20th	Day	25% 14% 30% 19% 9% 3	452
	21st to end	Day	23% 12% 33% 18% 10% 3	437
May	1st to 10th	Day	22% 11% 30% 22% 12% 3	423
	11th to 20th	Day	22% 8% 28% 20% 15% 7%	447
	21st to end	Day	11% 6% 25% 26% 20% 11%	529
June	1st to 10th	Day	11% 6% 28% 29% 20% 6%	630
	11th to 20th	Day	12% 7% 26% 29% 20% 6%	630
	21st to end	Day	12% 4 28% 30% 18% 7%	630
July	1st to 10th	Day	9% 3 18% 30% 24% 16%	621
	11th to 20th	Day	11% 3 20% 30% 22% 13%	618
	21st to end	Day	8% 3 21% 28% 30% 11%	586
August	1st to 10th	Day	9% 2 14% 30% 24% 21%	446
	11th to 20th	Day	11% 5% 18% 26% 25% 15%	439
	21st to end	Day	9% 3 16% 28% 28% 16%	495
September	1st to 10th	Day	15% 4 16% 28% 23% 14%	450
	11th to 20th	Day	10% 4 16% 22% 32% 16%	450
	21st to end	Day	16% 8% 20% 24% 22% 10%	450
October	1st to 10th	Day	14% 6% 24% 31% 17% 8%	450
	11th to 20th	Day	19% 15% 28% 30% 9%	443
	21st to end	Day	26% 13% 38% 18% 4 1	297
November	1st to 10th	Day	14% 12% 33% 27% 10% 4	270
	11th to 20th	Day	21% 21% 30% 20% 8% 1	270
	21st to end	Day	26% 11% 41% 19% 3	270
December	1st to 10th	Day	21% 19% 35% 16% 9% 1	270
	11th to 20th	Day	22% 16% 38% 20% 4	270
	21st to end	Day	25% 20% 32% 20% 2	297
January	1st to 10th	Night	21% 16% 35% 22% 6% 1	950
	11th to 20th	Night	24% 13% 36% 22% 5% 1	950
	21st to end	Night	22% 11% 35% 26% 5%	934
February	1st to 10th	Night	23% 11% 38% 24% 4	760
	11th to 20th	Night	21% 13% 35% 27% 3	743
	21st to end	Night	27% 11% 38% 21% 3	628
March	1st to 10th	Night	20% 11% 34% 27% 7% 1	760
	11th to 20th	Night	17% 13% 38% 25% 7% 1	760
	21st to end	Night	24% 9% 33% 26% 7% 1	836
April	1st to 10th	Night	18% 11% 36% 29% 6%	580
	11th to 20th	Night	22% 8% 35% 26% 9% 1	563
	21st to end	Night	23% 8% 32% 28% 9%	555
May	1st to 10th	Night	22% 7% 31% 32% 9% 1	540
	11th to 20th	Night	24% 5% 26% 29% 15% 1	531
	21st to end	Night	13% 3 24% 38% 20% 3	584
June	1st to 10th	Night	12% 2 24% 47% 16%	540
	11th to 20th	Night	9% 4 23% 43% 19% 1	540
	21st to end	Night	9% 3 21% 41% 23% 2	540
July	1st to 10th	Night	8% 2 14% 41% 28% 6%	525
	11th to 20th	Night	9% 2 15% 41% 30% 3	522
	21st to end	Night	5% 2 16% 45% 30% 1	591
August	1st to 10th	Night	7% 1 15% 41% 31% 4	537
	11th to 20th	Night	9% 1 13% 41% 31% 5%	534
	21st to end	Night	11% 2 15% 35% 34% 4	594
September	1st to 10th	Night	12% 3 16% 33% 31% 5%	600
	11th to 20th	Night	11% 3 15% 34% 33% 4	720
	21st to end	Night	15% 5% 20% 32% 22% 4	720
October	1st to 10th	Night	14% 6% 25% 33% 21% 2	720
	11th to 20th	Night	22% 10% 30% 28% 9% 1	720
	21st to end	Night	23% 12% 33% 24% 7%	792
November	1st to 10th	Night	15% 11% 33% 27% 13% 1	740
	11th to 20th	Night	22% 12% 31% 28% 6% 1	760
	21st to end	Night	23% 10% 32% 28% 6%	760
December	1st to 10th	Night	24% 14% 34% 22% 6%	760
	11th to 20th	Night	24% 12% 35% 24% 4 1	921
	21st to end	Night	30% 11% 32% 24% 3	1045

Page generated at 2024-04-22 09:25:40. Version ac07

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