McMinnville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the McMinnville clear sky chart from 2005-11-06 to 2024-03-08.

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	17% 8% 4 7% 6% 4 5% 5% 5% 6% 33%	78673
	Night	19% 9% 3 7% 6% 3 4 4 5% 6% 34%	80883
Transparency	Day	51% 9% 12% 16% 10% 2	78377
	Night	50% 10% 12% 16% 10% 3	80700
Seeing	Day	17% 11% 20% 26% 20% 6%	13873
	Night	20% 7% 19% 32% 20% 2	22840

By Month

Percentage Cloud Cover SW (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	32% 14% 6% 12% 9% 5% 5% 4 3 3 8%	2539
	11th to 20th	Day	35% 12% 4 9% 7% 3 5% 4 3 3 16%	2540
	21st to end	Day	31% 12% 5% 10% 8% 4 5% 4 4 4 13%	3114
February	1st to 10th	Day	24% 13% 5% 8% 8% 4 5% 5% 5% 7% 16%	1710
	11th to 20th	Day	23% 11% 6% 10% 8% 4 5% 5% 3 6% 18%	1665
	21st to end	Day	23% 13% 5% 10% 7% 5% 5% 5% 4 6% 18%	1471
March	1st to 10th	Day	24% 11% 5% 8% 7% 4 6% 6% 6% 7% 17%	1988
	11th to 20th	Day	25% 11% 6% 9% 8% 4 5% 3 4 6% 20%	1980
	21st to end	Day	24% 10% 5% 10% 9% 6% 6% 5% 6% 6% 14%	2204
April	1st to 10th	Day	22% 11% 5% 9% 8% 4 6% 5% 5% 6% 19%	2160
	11th to 20th	Day	20% 11% 5% 7% 7% 4 5% 5% 5% 5% 26%	2141
	21st to end	Day	17% 9% 3 8% 8% 4 6% 6% 6% 8% 25%	2340
May	1st to 10th	Day	12% 8% 4 7% 6% 4 5% 5% 6% 7% 35%	2448
	11th to 20th	Day	15% 8% 4 7% 7% 4 6% 5% 6% 8% 32%	2477
	21st to end	Day	17% 7% 3 6% 7% 4 6% 6% 7% 7% 30%	2723
June	1st to 10th	Day	17% 7% 4 8% 7% 3 5% 5% 5% 6% 33%	2520
	11th to 20th	Day	13% 8% 4 7% 7% 5% 6% 7% 7% 7% 29%	2520
	21st to end	Day	6% 5% 2 5% 5% 3 5% 5% 5% 7% 53%	2658
July	1st to 10th	Day	5% 4 2 4 4 3 4 5% 5% 6% 58%	2530
	11th to 20th	Day	6% 3 1 3 3 2 3 4 4 7% 63%	2520
	21st to end	Day	4 2 1 2 3 1 2 2 4 5% 74%	2727
August	1st to 10th	Day	2 3 1 4 4 3 3 4 5% 7% 64%	2328
	11th to 20th	Day	4 3 2 2 3 2 4 3 5% 7% 65%	2298
	21st to end	Day	5% 4 2 3 4 3 4 5% 6% 9% 57%	2464
September	1st to 10th	Day	5% 3 1 3 3 2 4 4 4 8% 63%	2160
	11th to 20th	Day	8% 6% 3 6% 6% 3 5% 4 6% 8% 44%	2138
	21st to end	Day	15% 5% 2 5% 6% 3 4 4 5% 6% 45%	1907
October	1st to 10th	Day	15% 7% 4 6% 6% 3 5% 5% 5% 7% 37%	1800
	11th to 20th	Day	16% 8% 4 9% 7% 3 5% 5% 6% 7% 30%	1800
	21st to end	Day	23% 10% 5% 7% 6% 3 4 4 4 6% 30%	1965
November	1st to 10th	Day	23% 13% 5% 10% 8% 4 5% 6% 6% 6% 15%	1556
	11th to 20th	Day	27% 12% 4 8% 8% 4 5% 3 4 5% 19%	1520
	21st to end	Day	24% 9% 5% 9% 7% 4 4 5% 4 5% 23%	1520
December	1st to 10th	Day	23% 12% 5% 9% 6% 4 5% 4 5% 4 22%	1520
	11th to 20th	Day	26% 12% 5% 8% 7% 4 5% 5% 7% 8% 13%	1928
	21st to end	Day	29% 14% 7% 12% 9% 4 5% 5% 4 3 7%	2794
January	1st to 10th	Night	30% 14% 5% 9% 8% 4 6% 5% 4 4 11%	4406
	11th to 20th	Night	33% 13% 5% 8% 6% 3 4 3 4 4 17%	4420
	21st to end	Night	35% 12% 5% 7% 6% 3 4 4 4 4 16%	4548
February	1st to 10th	Night	21% 12% 4 8% 7% 4 6% 6% 6% 7% 19%	2470
	11th to 20th	Night	22% 11% 3 7% 6% 3 5% 5% 4 6% 27%	2402
	21st to end	Night	21% 10% 4 9% 8% 3 5% 5% 5% 6% 23%	1981
March	1st to 10th	Night	20% 12% 4 9% 6% 4 5% 5% 5% 5% 25%	2131
	11th to 20th	Night	21% 9% 4 7% 7% 4 5% 5% 5% 7% 25%	1980
	21st to end	Night	23% 10% 4 7% 8% 5% 5% 5% 5% 6% 22%	2152
April	1st to 10th	Night	21% 11% 5% 9% 6% 3 4 5% 5% 6% 25%	1800
	11th to 20th	Night	16% 9% 4 7% 6% 3 5% 5% 5% 7% 33%	1762
	21st to end	Night	17% 8% 3 6% 5% 3 5% 6% 6% 9% 34%	1620
May	1st to 10th	Night	9% 6% 4 5% 6% 4 5% 5% 5% 7% 44%	1509
	11th to 20th	Night	13% 6% 3 6% 6% 3 5% 4 6% 9% 38%	1416
	21st to end	Night	11% 7% 3 6% 5% 3 5% 6% 7% 9% 38%	1552
June	1st to 10th	Night	13% 5% 3 6% 6% 3 6% 5% 5% 7% 40%	1440
	11th to 20th	Night	9% 7% 3 6% 6% 3 5% 6% 4 7% 44%	1440
	21st to end	Night	5% 4 2 4 3 2 4 3 3 6% 63%	1286
July	1st to 10th	Night	5% 2 1 2 2 2 2 3 4 6% 71%	1417
	11th to 20th	Night	4 2 1 2 2 1 3 2 3 6% 72%	1440
	21st to end	Night	2 1 1 1 1 1 2 2 3 3 83%	1586
August	1st to 10th	Night	2 2 1 3 2 2 2 3 4 7% 73%	1611
	11th to 20th	Night	3 2 1 2 3 2 2 2 3 5% 75%	1602
	21st to end	Night	6% 3 1 3 4 1 3 3 4 6% 66%	1891
September	1st to 10th	Night	5% 3 1 2 3 2 2 4 4 5% 70%	1800
	11th to 20th	Night	8% 5% 2 4 5% 3 4 4 6% 6% 52%	1819
	21st to end	Night	10% 5% 2 4 5% 3 4 4 5% 6% 54%	2052
October	1st to 10th	Night	12% 6% 3 5% 4 4 4 4 5% 5% 48%	2160
	11th to 20th	Night	15% 7% 3 5% 4 3 4 4 5% 8% 42%	2160
	21st to end	Night	20% 8% 4 5% 4 2 3 4 4 5% 39%	2390
November	1st to 10th	Night	23% 11% 4 7% 6% 4 5% 4 5% 6% 25%	2522
	11th to 20th	Night	28% 9% 4 7% 5% 3 6% 4 5% 5% 23%	2660
	21st to end	Night	22% 8% 4 8% 6% 3 4 5% 6% 6% 28%	2660
December	1st to 10th	Night	23% 11% 5% 7% 6% 3 5% 5% 5% 6% 25%	2660
	11th to 20th	Night	27% 11% 5% 8% 7% 4 4 5% 5% 7% 17%	3276
	21st to end	Night	26% 13% 5% 10% 7% 4 5% 4 6% 6% 15%	4862

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	78% 12% 4 3 2 1	2539
	11th to 20th	Day	73% 9% 6% 8% 2 1	2540
	21st to end	Day	73% 10% 6% 6% 4	3114
February	1st to 10th	Day	67% 12% 10% 8% 4	1710
	11th to 20th	Day	68% 11% 8% 8% 4 1	1674
	21st to end	Day	66% 10% 9% 8% 5% 2	1471
March	1st to 10th	Day	64% 11% 12% 9% 4	1988
	11th to 20th	Day	65% 8% 10% 11% 5% 1	1980
	21st to end	Day	70% 10% 11% 8% 1	2204
April	1st to 10th	Day	64% 10% 12% 11% 3	2160
	11th to 20th	Day	58% 10% 11% 12% 6% 3	2144
	21st to end	Day	57% 11% 13% 11% 7% 1	2340
May	1st to 10th	Day	47% 9% 16% 19% 9% 1	2448
	11th to 20th	Day	49% 11% 15% 17% 7% 1	2480
	21st to end	Day	50% 13% 17% 17% 3	2724
June	1st to 10th	Day	51% 9% 17% 18% 5% 1	2520
	11th to 20th	Day	50% 12% 19% 13% 5%	2520
	21st to end	Day	30% 8% 19% 27% 11% 4	2658
July	1st to 10th	Day	26% 8% 16% 23% 22% 6%	2461
	11th to 20th	Day	21% 7% 11% 27% 27% 6%	2445
	21st to end	Day	13% 4 11% 31% 34% 7%	2575
August	1st to 10th	Day	18% 8% 18% 32% 20% 5%	2312
	11th to 20th	Day	18% 7% 16% 30% 22% 7%	2298
	21st to end	Day	23% 8% 15% 30% 21% 3	2464
September	1st to 10th	Day	20% 8% 14% 27% 20% 11%	2160
	11th to 20th	Day	37% 11% 14% 18% 14% 6%	2138
	21st to end	Day	39% 9% 13% 20% 15% 5%	1907
October	1st to 10th	Day	45% 9% 10% 18% 15% 3	1800
	11th to 20th	Day	52% 9% 13% 12% 12% 1	1800
	21st to end	Day	58% 8% 9% 11% 13% 1	1965
November	1st to 10th	Day	68% 10% 9% 10% 3	1556
	11th to 20th	Day	67% 9% 9% 7% 6% 1	1520
	21st to end	Day	63% 10% 7% 9% 10% 1	1520
December	1st to 10th	Day	64% 9% 8% 10% 8% 1	1520
	11th to 20th	Day	67% 12% 11% 9% 1	1928
	21st to end	Day	79% 10% 5% 3 2	2794
January	1st to 10th	Night	72% 12% 7% 4 3 1	4406
	11th to 20th	Night	70% 9% 6% 10% 4 1	4420
	21st to end	Night	71% 9% 8% 7% 5% 1	4548
February	1st to 10th	Night	64% 11% 10% 11% 4	2470
	11th to 20th	Night	58% 10% 13% 10% 6% 2	2404
	21st to end	Night	60% 11% 12% 10% 6% 2	1981
March	1st to 10th	Night	59% 9% 12% 15% 5%	2131
	11th to 20th	Night	56% 10% 13% 14% 6% 1	1980
	21st to end	Night	61% 12% 14% 12% 1	2152
April	1st to 10th	Night	59% 10% 13% 13% 5%	1800
	11th to 20th	Night	50% 9% 17% 13% 7% 3	1762
	21st to end	Night	48% 11% 16% 16% 8% 2	1620
May	1st to 10th	Night	38% 10% 17% 25% 8% 2	1509
	11th to 20th	Night	43% 8% 19% 20% 6% 3	1416
	21st to end	Night	41% 14% 19% 19% 7%	1552
June	1st to 10th	Night	43% 9% 17% 24% 7% 1	1440
	11th to 20th	Night	38% 11% 21% 23% 6%	1440
	21st to end	Night	25% 7% 20% 31% 12% 5%	1286
July	1st to 10th	Night	17% 7% 16% 28% 23% 8%	1377
	11th to 20th	Night	15% 6% 12% 28% 31% 8%	1392
	21st to end	Night	7% 3 12% 34% 32% 12%	1498
August	1st to 10th	Night	13% 6% 15% 38% 21% 7%	1602
	11th to 20th	Night	14% 5% 16% 36% 21% 8%	1602
	21st to end	Night	20% 6% 13% 35% 21% 6%	1891
September	1st to 10th	Night	17% 7% 14% 29% 22% 11%	1800
	11th to 20th	Night	32% 8% 16% 22% 14% 9%	1819
	21st to end	Night	30% 8% 15% 20% 19% 7%	2052
October	1st to 10th	Night	38% 8% 10% 24% 17% 4	2160
	11th to 20th	Night	40% 10% 13% 19% 16% 3	2160
	21st to end	Night	46% 9% 11% 15% 15% 3	2390
November	1st to 10th	Night	58% 10% 11% 14% 6%	2522
	11th to 20th	Night	63% 9% 9% 9% 7% 2	2660
	21st to end	Night	56% 11% 10% 9% 12% 2	2660
December	1st to 10th	Night	59% 10% 10% 10% 10% 1	2660
	11th to 20th	Night	66% 11% 10% 9% 4	3276
	21st to end	Night	65% 15% 11% 6% 2	4862

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	39% 17% 17% 16% 9% 2	180
	11th to 20th	Day	36% 12% 16% 19% 12% 4	180
	21st to end	Day	27% 12% 19% 21% 18% 3	388
February	1st to 10th	Day	28% 15% 22% 16% 16% 3	370
	11th to 20th	Day	30% 14% 25% 17% 12% 2	365
	21st to end	Day	27% 21% 21% 19% 11% 1	335
March	1st to 10th	Day	26% 17% 24% 23% 8% 2	449
	11th to 20th	Day	25% 16% 20% 22% 15% 2	420
	21st to end	Day	27% 16% 23% 22% 11% 1	462
April	1st to 10th	Day	26% 19% 21% 19% 11% 5%	420
	11th to 20th	Day	27% 15% 24% 21% 8% 5%	412
	21st to end	Day	20% 15% 25% 25% 13% 3	420
May	1st to 10th	Day	14% 16% 23% 26% 17% 4	423
	11th to 20th	Day	22% 11% 17% 27% 17% 6%	448
	21st to end	Day	13% 9% 20% 28% 20% 9%	485
June	1st to 10th	Day	16% 11% 20% 26% 20% 7%	450
	11th to 20th	Day	14% 12% 26% 28% 16% 4	450
	21st to end	Day	5% 8% 21% 35% 24% 6%	588
July	1st to 10th	Day	6% 4 16% 37% 30% 8%	456
	11th to 20th	Day	4 5% 18% 35% 29% 10%	444
	21st to end	Day	2 3 13% 33% 38% 11%	487
August	1st to 10th	Day	3 2 13% 33% 34% 15%	447
	11th to 20th	Day	3 3 9% 33% 35% 18%	437
	21st to end	Day	5% 4 17% 36% 29% 9%	495
September	1st to 10th	Day	6% 4 23% 29% 30% 8%	450
	11th to 20th	Day	10% 6% 17% 27% 31% 8%	450
	21st to end	Day	14% 8% 22% 30% 19% 6%	450
October	1st to 10th	Day	17% 9% 21% 24% 21% 8%	450
	11th to 20th	Day	19% 10% 16% 26% 19% 9%	450
	21st to end	Day	25% 14% 26% 18% 11% 7%	480
November	1st to 10th	Day	26% 19% 20% 21% 11% 3	214
	11th to 20th	Day	26% 13% 23% 15% 16% 7%	180
	21st to end	Day	26% 14% 19% 18% 17% 6%	180
December	1st to 10th	Day	33% 11% 15% 21% 13% 7%	180
	11th to 20th	Day	32% 13% 23% 20% 9% 2	180
	21st to end	Day	33% 17% 19% 17% 13% 2	198
January	1st to 10th	Night	34% 13% 16% 21% 13% 2	760
	11th to 20th	Night	31% 12% 16% 23% 17% 2	760
	21st to end	Night	28% 7% 16% 29% 17% 3	836
February	1st to 10th	Night	24% 11% 19% 29% 15% 2	760
	11th to 20th	Night	25% 11% 20% 27% 17% 1	744
	21st to end	Night	24% 15% 21% 29% 11%	628
March	1st to 10th	Night	24% 11% 23% 28% 14% 1	750
	11th to 20th	Night	22% 9% 20% 33% 15% 1	720
	21st to end	Night	27% 9% 24% 26% 14% 1	792
April	1st to 10th	Night	25% 10% 21% 27% 17% 1	720
	11th to 20th	Night	19% 10% 24% 31% 14% 1	694
	21st to end	Night	21% 7% 20% 35% 16% 1	540
May	1st to 10th	Night	11% 7% 24% 39% 18% 1	429
	11th to 20th	Night	14% 5% 18% 38% 23% 1	354
	21st to end	Night	12% 5% 22% 37% 22% 1	389
June	1st to 10th	Night	13% 5% 19% 39% 24%	360
	11th to 20th	Night	11% 4 24% 42% 18% 1	360
	21st to end	Night	7% 2 19% 49% 23%	360
July	1st to 10th	Night	3 1 14% 51% 29% 1	350
	11th to 20th	Night	5% 1 19% 50% 24% 1	348
	21st to end	Night	2 1 11% 51% 34% 1	404
August	1st to 10th	Night	3 1 9% 42% 40% 5%	537
	11th to 20th	Night	4 1 8% 39% 45% 3	534
	21st to end	Night	7% 2 15% 43% 31% 2	703
September	1st to 10th	Night	5% 2 18% 40% 33% 2	720
	11th to 20th	Night	8% 4 14% 35% 34% 5%	720
	21st to end	Night	11% 5% 14% 40% 27% 4	720
October	1st to 10th	Night	15% 3 22% 32% 25% 3	720
	11th to 20th	Night	16% 6% 15% 33% 25% 5%	720
	21st to end	Night	24% 7% 21% 26% 18% 4	792
November	1st to 10th	Night	24% 10% 19% 32% 15%	740
	11th to 20th	Night	30% 10% 21% 25% 13% 1	760
	21st to end	Night	25% 7% 20% 28% 17% 2	760
December	1st to 10th	Night	26% 8% 18% 29% 16% 2	760
	11th to 20th	Night	32% 10% 21% 24% 13% 1	760
	21st to end	Night	31% 13% 21% 24% 10% 1	836

Page generated at 2024-03-05 04:23:58. Version ac07

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